Blender Wiki Gamekit2 PDF
Blender Wiki Gamekit2 PDF
Table of Contents
About Blender Wiki Gamekit2 PDF. 1
Modifications to the wiki content 1
Previous versions. 1
Where to find this PDF. 2
How to contact me. 2
Open Content License 3
Foreword by Ton Roosendaal 4
About this book. 6
The book contains: 6
Ouickstart 7
Simple face mapping 7
Using 2D applications to map the face. 11
Introduction to 3D 13
Purpose of This Chapter 13
General Introduction to 3-D 13
XY axes. 13
Points 14
Lines. 14
Polygons. 15
3-D. the third dimensioa 15
Z axis. 15
Points 15
Lines. 16
Polygons. 16
3-D computer graphics 16
Terminology. 17
Triangles, quads 17
Mesh 17
Primitives 18
Faces 18
Materials 19
Textures 19
Image maps 19
UV mapping. 19
UV vs. XY coordinates 20
Viewing 3-D space. 21
Standard 21
Interactive (freel 21
Cameras 22
View modes 22
Lights 22
Transformations 23
Game Engines and Aspects of a Good Game. 24
What is a game engine?. 24
Blender's game engine — Click and drag game creation 25
"True" and "fake" 3-D game engines. 25
Good games 25
Conclusion. 26
Blender Wiki Gamekit2 PDF
Table of Contents
Blender Basics . 27
The Interface. 27
Blender's Interface Concept 27
Keyboard and mouse 27
General Usage . 28
The Window System 28
The default Blender scene. 28
The Window Header 30
Changing Window Frames 31
Console Window & Error Messages 31
Window types . 32
Button Window Contexts. 33
Menus 34
Panels. 34
Buttons and Controls 35
Color Selector 37
Screens 37
Adding a new Screen 38
Deleting a Screen 38
Scenes 38
Adding a new Scene 39
Deleting a Scene 39
User Preferences . 39
Navigating in 3D 40
Using the keyboard to change your view. 40
Using the mouse to change your view 40
Selecting of Objects. 41
Copying and linking 41
Copy . 41
Linked Copy 41
Data Browse Button . 42
Linking . 42
Manipulating Objects 43
Grah 43
Rotate 43
Scaling 43
Transform Properties 43
Edit Mode 44
Vertices. Edges and Faces 45
Vertex. Edge and Face Modes 46
Basic Editing . 47
Specials 47
Pumpkin Run - Playing with 3D game technology. 50
Modeling an environment 50
Appending an object from an other scene 54
Start your (Game) Engines !. 56
Realtime Materials 57
Interactivity 58
More control 61
Camera control 61
Real-time Light 62
Blender Wiki Gamekit2 PDF
Table of Contents
Pumpkin Run - Playing with 3D game technology
Object Animation 63
Refining the scene 65
Adding Sound to our scene 66
Last words 67
Tube Cleaner. 68
Loading the models 68
Controls for the base and cannon 69
Upwards Movement 70
Shooting 72
More control for the gun 74
An enemy to shoot at . 76
Pinball . 79
Use of the elements 79
Bumpers 81
The Sewer . 82
Subracer. 84
Ship setup 85
Sensors 87
Controllers 87
Actuators 87
Guns 88
Game Objects 89
Turbo crate 89
Mine 89
Gate 90
GLSL Mist 92
Blender Basic Network setup - Boil it down to the basics. 94
Ingredients 94
Server.pv. 94
Script 94
Explanation 95
Client.pv: 99
Script 99
Explanation 99
Appetite for more 100
Game Character Animation using Armatures 101
Preparing the Mesh. 101
Working with Bones. 101
Creating Hierarchy and Setting Rest Positions 102
Naming Bones. 102
Parenting Bones 103
Basic Layout . 104
Coordinate System Conventions. 104
Establishing Mesh Deformation Vertex Groups 104
Creating Groups 105
Testing the Skinning 106
Blender Wiki Gamekit2 PDF
Table of Contents
Game Character Animation using Armatures
Pose Mode. 106
Weight Editing 107
Animation 109
Multiple Actions and Fake Users. 109
Creating an Idle Cycle 110
Creating a Walk Cycle 112
Game Logic 115
Flying Buddha Memory Game. 118
Accessing game objects 118
LogicBricks. 119
Shuffle Python script 119
Apricot OpenGame Project: Yo Frankie! . 122
Creative Commons 122
Yo Frankie! Blender Game Engine Logic By Campbell Barton 123
Logic Sharing. 123
States 124
Logic Elements 125
Frankies Logic 131
Building a simple test level 136
Level Design Physics/Logic 136
Physics Objects 136
Materials 136
Properties 136
Starting A New Level Using Linked Groups. 138
Modify Apricot Files 140
Reference 143
Real-time Materials 143
Texture Face Materials 143
Blender Multitexture Materials. 144
GLSL Materials 144
Lamps in the game engine 147
UV Texturing 148
Blenders Game Engine 160
Options for the game engine 160
Logic Buttons. 161
Properties 164
Example of some Logic 164
The Blender laws of physics 165
Soft Bodies by Erwin Coumans . 167
Bullet Game Engine Features 170
Sound Buttons . 174
Performance and design issues . 175
Game Logic Bricks. 176
Sensors 176
Controllers 189
Simple Logical Controllers 190
Expression Controller 190
Python Controller. 192
iv
Blender Wiki Gamekit2 PDF
Table of Contents
Reference
State System. 192
State GUI 193
Actuators. 194
(Shape) Action Actuator 194
Motion Actuator. 196
Constraint Actuator . 199
Ipo Actuator 204
Camera Actuator 206
Sound Actuator 207
Property Actuator. 208
Edit Object Actuator 209
Scene Actuator 212
Random Actuator 213
Message Actuator. 215
Game Actuator 216
Visibility Actuator 216
2D Filter Actuator 216
Parent Actuator 217
State Actuator. 218
Game engine Python 218
Text Window. 219
BGE Python 220
GameLogic Module 224
Rasterizer Module . 225
GameLogic. globalDict 225
GameKevs Module 226
PhvsicsConstraints Module. 226
Message Body . 233
A ppendix. 234
Getting Blender 234
Installation of Blender 234
Getting Support 234
Blender Foundation and Institute 234
Goals 234
Organization 235
Links to the Blender Community. Books and Websites 235
Glossary. 235
About Blender Wiki Gamekit2 PDF
This is an unofficial PDF version of the Blender Wiki Gamekit2 pages.
I produced this PDF copy for my personal use since I needed it to learn using Blender, and I could not find an
up to date alternative to my knowledge. I've read that Blender documentation is released under the Open
Content License ( http://opencontent.org/opl.shtml) . This license is reported at the end of this pages, below. I
am trying to stick to this licence, but i'm no license expert: if you feel something is wrong, just let me know
why and possibly how to fix.
Modifications to the wiki content
I did not modify the content of the wiki pages except for removing the parts typical of a web page, which are
not needed in a "book", since you don't have to browse through web links, but scroll pages.
Previous versions
In the past i built the wiki manual pdf using different tools to:
• collect links ( http://gemal.dk/mozilla/linkv.html )
• download pages and editing them ( http ://w w w .php . net )
• build the pdf with images ( http://www.htmldoc.org )
• build the pdf bookmarks ( http://ipdfbookmarks.altervista.org )
trying to automate everything as possibile... I never liked at all that workflow, but it worked in some way.
For this release i managed to use only two tools:
• http://www.php.net
Used it to scan the base page, find links, download locally pages and images, and build the .book for
the next tool
• http://www.htmldoc.org
Open the .book file and click "generate". After a minute or so, the PDF is ready.
Still, there are some (minor) problems:
• many internal links are broken: some of them work and some do not. I don't know why. When they
work, often they jump to the "previous" page they refer to. Try to advance of one page, in case;
• there are strange symbols here and there: the HTMLdoc version I have (1.8.27) is not UTF-8
compatible, it renders web pages using ISO-8859-x encodings. I use ISO-8859-1 since i think it's the
best for english Language. New versions or other tools may improve this aspect, in the future. Is not
something that makes text difficult to understand, though.
• Size is huge: there are many pages, and many big images and they're useful. I could reduce quality
setting for JPGs below 85%, if needed but quality will suffer. Compressing the PDF does not change
much the size (tried 7z ultra)
You should be able to know what's changed since the last release browsing here:
http://wiki.blender.org/index.php ?namespace=&target=Doc:2.4/Books/GameKit 2&title=Special:RecentChangesLink
15/02/2011 12:39:15
About Blender Wiki Gamekit2 PDF Where to find this PDF
Where to find this PDF
Up to now, you should be able to find it here: http://pdf.letworvinteractive.com . If any change should happen,
i'll post on major forums/blogs for everyone to know.
How to contact me
I do this in the spare time so i can't spend too much time on it but if you want to suggest me improvements or
other ways to do this, or alternatives, please feel free to do so. Here's how: "m.ardito" is the username and the
domain is "libero.it". you know how to use them ;). Please don't post the "reconstructed" address, in no web
page, blog, mailing list or newsgroup, anywhere. I already have enough spam to deal with! Thanks.
Have fun! Marco Ardito
15/02/2011 12:39:15
Open Content License
OpenContent License (OPL)
Version 1.0, July 14, 1998.
This document outlines the principles underlying the OpenContent (OC)
movement and may be redistributed provided it remains unaltered.
For legal purposes, this document is the license under which
OpenContent is made available for use.
The original version of this document may be found at
http : //opencontent . org/opl . shtml
LICENSE
Terms and Conditions for Copying, Distributing, and Modifying
Items other than copying, distributing, and modifying the Content
with which this license was distributed (such as using, etc.) are
outside the scope of this license.
1 . You may copy and distribute exact replicas of the OpenContent
(OC) as you receive it, in any medium, provided that you conspicuously
and appropriately publish on each copy an appropriate copyright notice
and disclaimer of warranty; keep intact all the notices that refer to
this License and to the absence of any warranty; and give any other
recipients of the OC a copy of this License along with the OC . You may
at your option charge a fee for the media and/or handling involved in
creating a unique copy of the OC for use offline, you may at your
option offer instructional support for the OC in exchange for a fee,
or you may at your option offer warranty in exchange for a fee. You
may not charge a fee for the OC itself. You may not charge a fee
for the sole service of providing access to and/or use of the OC via
a network (e.g. the Internet), whether it be via the world wide web,
FTP, or any other method.
2 . You may modify your copy or copies of the OpenContent or any portion
of it, thus forming works based on the Content, and distribute such
modifications or work under the terms of Section 1 above, provided that
you also meet all of these conditions:
a) You must cause the modified content to carry prominent notices
stating that you changed it, the exact nature and content of the
changes, and the date of any change.
b) You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the OC or any part
thereof, to be licensed as a whole at no charge to all third parties
under the terms of this License, unless otherwise permitted under
applicable Fair Use law.
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the OC, and
can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the OC, the distribution of the whole must be on the terms of this
License, whose permissions for other licensees extend to the entire
whole, and thus to each and every part regardless of who wrote it.
Exceptions are made to this requirement to release modified works
free of charge under this license only in compliance with Fair Use
law where applicable.
15/02/2011 12:39:15
Open Content License Foreword by Ton Roosendaal
3. You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to copy,
distribute or modify the OC . These actions are prohibited by law
if you do not accept this License. Therefore, by distributing or
translating the OC, or by deriving works herefrom, you indicate
your acceptance of this License to do so, and all its terms and
conditions for copying, distributing or translating the OC .
NO WARRANTY
4. BECAUSE THE OPENCONTENT (OC) IS LICENSED FREE OF CHARGE, THERE
IS NO WARRANTY FOR THE OC, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS
AND/OR OTHER PARTIES PROVIDE THE OC "AS IS" WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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SHOULD THE OC PROVE FAULTY, INACCURATE, OR OTHERWISE UNACCEPTABLE
YOU ASSUME THE COST OF ALL NECESSARY REPAIR OR CORRECTION.
5. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
MIRROR AND/OR REDISTRIBUTE THE OC AS PERMITTED ABOVE, BE LIABLE
TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL
OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO
USE THE OC, EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED
OF THE POSSIBILITY OF SUCH DAMAGES.
Foreword by Ton Roosendaal
The first "Blender GameKit" was published end of 2002. It has marked the beginning of a new era for
Blender, as an open source project being developed and maintained by the on-line community themselves. It
also marked the beginning of the Blender Foundation, as a publisher of Blender books, to enable financing its
goals. In just a few months GameKit revenues proved to be sufficient to allow myself to work full-time on
Blender projects. So let me begin with thanking everyone who has helped realizing it, and who has supported
Blender by purchasing a copy !
The success story of Blender in the six years after are well known now. We've firmly established it in the top
ten of 3D creation suites - up-to-par with commercial software - and we can only be very proud to have helped
creating the most popular free and open 3D tool ever! There was just one aspect of Blender that got stuck
behind too much... the logic tools and Game Engine (GE). The complexity of integrating a tool with a GE was
just too much of a challenge. Luckily, in a relatively short time, thanks to three remarkable events it came
completely back:
• Erwin Coumans, original developer of the GE, helped integrating his new and very advanced
collision/physics system in Blender. During 2007 his Bullet library became one of the most important
reasons of artists to use the GE.
• Early 2008, a new developer Benoit Bolsee fixed like every open bug report in the GE. In just a few
months he brought back the open issues from over a 100 to less than 10. Stability and predictability is
crucial for game engines !
• The Blender Foundation's "Apricot" Open Game project then decided to start using the GE as well. A
lot of work was realized on more advanced logic editing and well integrated usage of materials,
shaders and animation features. Apart from Benoit, Brecht van Lommel and Campbell Barton deserve
to be credited for this breakthrough. Credits also should go to artist Chris Plush, who proved us the
renewed GE's value by creating in a mere four hours work a prototype of the YoFrankie game!
15/02/2011 12:39:15
Open Content License Foreword by Ton Roosendaal
Here's the reason why you're now holding this new and fully revised edition of the Gamekit in your hands.
This book always was a great introduction for people into 3D games creation, and with the unleashed power
of Blender 2.48, it's more than ever a book that will help you making stunning and advanced interactive 3D
environments, multi-level 3D games with menus, or even 3D documentation for industrial products.
I'm also very grateful that we got the interest from the original editor and designer of the Game Kit back to
update this book. Many thanks go to Carsten Wartmann, renowned author of plenty of Blender books, and to
designer Samo Korosec.
I wish you a lot of pleasure reading this book!
Amsterdam, november 2008
Ton Roosendaal Chairman Blender Foundation
15/02/2011 12:39:15
About this book
Blender offers you a new and unique way to explore interactive 3D graphics. This book will guide you
through many aspects of making your own games and interactive 3D graphics with Blender.
You can have fun with the ready made games on the DVD instantly, but changing them or creating your own
game is also great fun.
Blender is a fully integrated 3D creation suite. It has all the tools for making linear animation and non-linear
(interactive) 3D graphics. All of these features are provided in one single application and gives the artist a
very smooth workflow from design, to modeling, animating and on-to publishing of 3D content. For example
if you needed to make a demo trailer of a game you would need a modeler, a renderer, a video editing
application and the game engine itself to produce the video. Blender offers you all these tools combined to
produce interactive and linear 3D content.
With Blender, we give you the tools you need to make your creative ideas come true. With this book will
show you how to achieve this using Blender.
The book contains:
• Example game scenes to play with
• Example games and tutorial scenes to change and personalize
• Blender basics for making interactive 3D graphics
• 3D game technology basics
• Advanced tips and topics from professional Blender artists
• References for the Blender game engine
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15
Quickstart
Have you ever wanted to personalize a computer game? Well, many game level editors will give you that
possibility, but Blender goes a step further, by allowing you to create a completely new game.
In this quick-start chapter, I will show you how to map a face onto a game character.
□
qs-mad: Calli going mad...
The game character used here was made by Reevan McKay. You can read more about this in Chapter
Character Animation BGE . which will show you many other things about character animation.
In Figure [qs-mad] you can see an image of an real time 3D animation created using the method which will be
briefly described in this chapter. The scene is called
Tut or ials /Quickstart /Call IGoinqMad. blend .
This quick start tries to be as self-contained as possible. Although it is good if you already know something
about graphics, if you follow the instructions step-by-step all should go well.
Note
If you have not installed Blender yet, please do so
Simple face mapping
This section will show how to put a new face onto a ready-made character, there are some drawbacks to this
method but it will get you started quickly.
Start Blender by double clicking its icon. It will open a screen as shown in Figure [qs-fs]
15/02/2011 12:39:15
Quickstart
Simple face mapping
J£l^ Vlgw SaiBBl piaml^OgjctMsJp - 1 jjjjj .fl^^j [5!^ " j [EHt E3 B
nS3* P«Hi OT.J.Ofe—a
JF|MM»t
b7"»
Hw I Mrtt
OQWCiin>
1 5tt** I *M«
Lit "r- I j-:-.;<
□
qs-fs: Blender just after starting it
Locate the "File"-menu on the top left of the screen and choose "Open" by clicking it with the left mouse
button (LMB). A big File Window appears which is used for all Blender loading and saving operations.
|p j | dftDokuiMms>Bft n a etF o u n <i alio n\Q ameKitv aBooBBi e nmvatiicksiafa
| tj | Facemappiriij_Oa. bland
Open File
Cancel
CalliGoingMad.blend
CalliQoingMad.blendl
Face mappi n g_flO.Blein<J
Face mappi n g_0t)_bl8nd1
10B
Frae: 2390.75 1 M8 Files: (i) A (1.143) 3,963 MB
"
□
qs-fw: Blender FileWindow
The button labeled with a "P" at the upper left corner of the File Window puts you one directory up in your
path. The Menu Button L*J below brings you back to the last directories you have visited, as well as your
mapped drives in Windows. Click and hold it with the left mouse button to change to your DVD drive.
Now enter the directory Tutorials /Quickstart/ and click with the left mouse on
Facemappina 00. blend . Confirm your selection by clicking "Open" at the top right of the FileWindow.
Blender will load the file needed for the tutorial.
Note
Please have a look at Section
[file:///home/user/my/blender/wiki/GE_GK2/Source/Quickstart/Quickstart.html#BlenderBasics Blender
Basics] for a explanation on how we will call interface elements and keyboard shortcuts (i.e. PKEY) in the
tutorials.
To have a quick look what this file is about, press CTRL-RIGHT ARROW. The window layout changes to a
15/02/2011 12:39:15
Quickstart
Simple face mapping
bigger view of the character. Now press PKEY and the game engine will start. Using the controls from the
table, walk around to have a closer look at the character.
Controls/Keys
Description
WKEY
Move forward
DKEY
Move left
AKEY
Move right
SKEY
Move backwards
CTRL
Shoot
SPACE
Duck
Stop the game engine by pressing ESC when you have seen enough. Press CTRL-LEFT ARROW to return to
the window layout which we will now use to map a different face.
Move your mouse cursor over the left window with the 3D view of the head and press TAB. This will start the
so-called "EditMode", which is used to change the object itself but also manage and change textures on
objects.
All polygons which belong to the face are now outlined and you can see them also in the right view showing
the 2D texture image of the face. This procedure is called mapping and will make the 2D image appear where
we want it on the 3D object.
□
qs-map: 3D head and 2D facemap
Use the menu "Image->Open..." while holding CTRL or STRG-ALT-0 in the right Image Window. A File
Window (in this case an Image File Window) will open and lets you browse through your harddiscs and the
DVD again. Go to the directory Tutorials/Quickstart/textures/.
If called while holding CTRL the Image File Window displays little thumbnail images to ease the choice of
images (see Figure [qs-images]).
15/02/2011 12:39:15
Quickstart
Simple face mapping
p ai\Donum s^te^e i*n oe rFo und ati on\eameK.iiv£\Boo <\e ien osvqu K*siarwsxiur*s\
Open I mag?
Cancel
J Open image \f?\} Q | Relative Paths
□
qs-images: Image File Window
Note
You can also choose a picture of you or an other person. But if you are a beginner, I would suggest to use the
supplied image for your first attempt. Blender can read and write PNG (*.png), Targa (*.tga) and JPEG
(*.jpg) and most all other common image formats.
Click on the image Carsten.jpg (yes, its me, your tutorial writer making a silly face) and click the "Open
Image" Button on the top right of the Image File Window to load it. The image will immediately appear in the
3D view to the left.
Note
Depending on your screen resolution you may need to zoom the right Image Window out a bit. Use the PAD-
and PAD+ keys for zooming.
The dimensions of my silly face don't fit the previous mapping, so it'll look a bit distorted. Also, the color may
not match exactly, making it look like a cheap mask.
Now move your mouse over the Image Window on the right and press AKEY-AKEY (twice AKEY), this
selects (yellow color) all the control points here, called vertices in Blender. Now press GKEY and move your
mouse, and all vertices will follow and you can watch the effect on the 3D View. Try to position the vertices
in the middle of the face, using the nose as a reference. Confirm the new position with the left mouse button.
If you want to cancel the move, press the right mouse button or ESC.
Note
15/02/2011 12:39:15
10
Quickstart
Using 2D applications to map the face
To have a better look at the head in the 3D View, you can rotate the head around using the middle mouse
button and moving the mouse (if you are using a 2 button mouse, hold ALT and use the left mouse button).
To refine the placement of the texture on the head, you may now need to move the vertices more. Move your
mouse over to the Image Window on the right and press AKEY to de-select all vertices (they will turn purple).
Now press BKEY. This will start the Border Select, and a crosshair will appear. Press and hold the left mouse
button to draw a rectangle around vertices you want to select and release the mouse button. Now you can
move these vertices by pressing GKEY and using the mouse. Press LMB to confirm the move. Control the
effect by watching the head on the 3D View. Single vertices can be selected by using the right mouse button
(RMB), SHIFT-RMB adds a single vertex or deselects when used on a already selected vertex.
Note
Don't give up too soon! Mapping a face needs practice, so take a break and play with the games on the DVD,
and try again later.
If you want to look at your creation, switch to the full screen scene by pressing CTRL-RIGHTARROW and
start the game engine with PKEY.
Using 2D applications to map the face
Maybe you are already an artists for computer graphics who wants to step into the 3D graphics. So it is very
possible that you know 2D painting programs well. This part of the tutorial will give you a brief guide on how
to use a 2D painting program to montage a face into the facemap. You should know how to work with layers
in your application (if not please consult the documentation of your image editing program). I use the free
software (GPL) GIMP ( http://www.gimp.org/ ) but of course any other image manipulation programs (which
supports layers) will do.
15/02/2011 12:39:15
11
Quickstart Using 2D applications to map the face
1. Load the image swat-face.tga from the DVD and the face you want to use in your paint program.
2. Place the new face in a layer below the "swat-face.tga" and make the upper layer slightly transparent
so that you can see the new face shining through.
3. Scale and move the layer containing the new face so that it fits to the "swat-face.tga" layer. Use the
eyes, mouth and the nose as guide to match them up. Also try to match the colors of the layers using
the color tools of your 2D program.
4. Make the upper layer non transparent again
5. Now use the eraser from your 2D paint program to delete parts of the upper layer, the new face will
appear at these points. Use a brush with soft edges so that the transition between the two layers is soft.
6. Collapse the layer to one and save the image as a PNG (*.png) or JPEG (*.jpg) image. Maybe do
some final touch-ups on the collapsed image, like blurring or smearing areas of transition. [[Image:]]
Now load the scene Facemapping QQ.blend . Press TAB with your mouse over the 3D View on the left
to enter Edit Mode. Move your mouse over to the right Image Window and choose the menu
"Image->Replace" this time. This will replace the current texture in the file with your self-made
texture. Locate the image with your face on your disks, select it with the left mouse button and press
"Open Image" in the Image File Window. The new texture will now appear on the head. Switch to the
full screen again (CTRL-RIGHTARROW) and test the scene by starting the game engine with PKEY.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15 12
Introduction to 3D
by Michael Kauppi
Purpose of This Chapter
This chapter will introduce you to the world of three dimensional (3D) computer graphics, first by introducing
the general concepts behind 3D and then by showing how those concepts are used in computer graphics.
Then, it will introduce you to game engines, especially Blender's game engine, and three aspects that are often
found in good games. This chapter is aimed at those who have little or no experience in 3D or with game
engines.
General Introduction to 3-D
We'll begin our journey into 3-D with an overview of 2-D because most people reading this should already
know the concepts behind 2-D or least be able to grasp them fairly quickly.
XY axes
You can think of 2-D as being a flat world. Imagine you put a blank piece of paper on a table, and look down
at that paper.
If that paper represented the 2-D world, how would you describe where things are located? You need some
kind of reference point from which to measure distances.
This is generally done by drawing two lines, called axes: one horizontal and the other vertical (Figure 3-1).
The horizontal line is called the X-axis, and the vertical line is called the Y-axis. Where the axes cross is your
reference point, usually called the "origin".
Origin
Along these axes, imagine a series of regularly spaced hash marks, like the lines on a ruler. To describe where
something is, you count out the distance along the X and Y axes. Distances to the left and below the origin on
the X and Y- axes respectively are negative, while distances to the right and above the origin on the X and Y
axes respectively are positive (Figure 3-2).
15/02/2011 12:39:15 13
Introduction to 3D
XY axes
">Y
-X
+x
For example, if you wanted to describe where the dot in Figure 3-2 is located, you would count out 4 units
along the X-axis (known as the X coordinate) and 5 units along the Y-axis (known as the Y coordinate).
Now with a default origin and XY coordinates, we can begin to describe 2-D geometry.
Points
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s
-X
+x
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The dot from Figure 3-3 is the simplest object that can be described in 2-D, and is known as a point. To
describe a point you only need an X and a Y coordinate.
Lines
Y
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X
The next simplest object we can describe in 2-D is the line. To describe a line, you only need to describe two
points (Figure 3-4).
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14
Introduction to 3D
Polygons
Polygons
By connecting three or more lines, you can begin to describe shapes, known as polygons. The simplest
polygon is the three-sided triangle, next is the four-sided quadrangle, or quadrilateral, (usually shortened to
quads), and so on, to infinity. For our purposes, we'll only work with triangles and quads.
With this knowledge, it's now time to expand from 2-D to 3-D.
3-D, the third dimension
As the name implies, 3-D has an extra dimension but the concepts we covered in the 2-D discussion above
still apply.
Zaxis
+ X
*z
Just like 2-D, we need a reference point from which to describe the location of things in 3-D. This is done by
drawing a third axis that is perpendicular to both the X and Y axes, and passes through the origin. This new
axis is usually called the Z-axis, and values above and below the origin are positive and negative respectively
(Figure 3-5). By using this new axis we can describe objects as they exist in the real world.
Points
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To describe a point in 3-D, we now need three coordinates: the X, Y and Z coordinates (Figure 3-6).
15/02/2011 12:39:15
15
Introduction to 3D
Lines
Lines
I
As in 2-D, we can describe a line by defining two points, but now our line does not have to lay flat, it can be
at any angle imaginable (Figure 3-7).
Polygons
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By connecting lines, we can form polygons just like in 2-D. Our polygons, just like our lines, are no longer
confined to the flat 2-D world (Figure 3-8). Because of this, our flat 2-D shapes can now have volume. For
example, a square becomes a cube, a circle becomes a sphere and a triangle becomes a cone (Figure 3-9).
Now with the basics of 3-D covered, let's see how they relate to 3-D computer graphics.
3-D computer graphics
By now, you should have the general concepts of 3-D in mind. If not, go back and reread the previous
sections. Having these concepts in mind will be very important as you proceed through this guide. Next, we'll
show you how the concepts of 3-D are used in 3-D computer graphics, also known as computer graphic
15/02/2011 12:39:15
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Introduction to 3D
images (CGI).
3-D computer graphics
Terminology
A slightly different set of terms is used for CGI. Table 3-1 show how those terms relate to what you have
learned so far.
3-D term
Related CGI term
Point
Vertex
Line
Edge
Polygon
Polygon
Table 3-1. CGI Terminology
Armed with our new terminology, we can now discuss CGI polygons.
Triangles, quads
While theoretically, a polygon can have an infinite number of edges, the more edges there are, the more time
it takes a computer to calculate that shape. This is why triangles and quads are the most common polygons
found in CGI, they allow the creation of just about any shape and do not put too much stress on the computer
to calculate. But how do you form shapes with triangles and quads?
Mesh
As discussed before, our polygons are no longer confined to the flat 2-D world. We can arrange our polygons
at any angle we choose, even "bending" our polygons if necessary. By combining a series of polygons
together at various angles and sizes, we can create any 3-D shape we want.
For example, six squares can combined to make a cube, and four triangles and a square form a pyramid
(Figure 3-10). By increasing the number of polygons and manipulating their locations, angles and sizes we
can form complex objects (Figure 3-1 1). As you can see, the more complex an object, the more it takes on a
mesh-like appearance. In fact, the object in Figure 3-11 is being viewed in "wire mesh" mode. You'll often
hear the term "mesh" used to describe any combination of CGI polygons.
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17
Introduction to 3D
Mesh
Primitives
As shown above, we can create shapes by combining polygons, but to form basic shapes by hand (such as
spheres, cones, and cylinders) would be very tedious. So 3-D applications like Blender have preprogrammed
shapes called "primitives" that you can quickly add to a 3-D scene. Blender's mesh primitives include: planes,
cubes, spheres, cones, cylinders and tubes. There are other primitives as well (not all of them mesh based),
and you will learn about them as you develop your Blender skills.
Faces
Polygons can be faced or unfaced. You can think of an unfaced polygon as being made of just wire, while a
faced polygon has a "skin" stretched over that wire (Figure 3-12). When you tell Blender to draw your 3-D
scene, called rendering, the faced polygons will appear solid, while the unfaced polygons will appear as holes
(Figure 3-13).
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18
Introduction to 3D
Materials
Materials
Look at objects around you, they have many characteristics. Some are shiny, some are matte. Some are
opaque, some are transparent. Some appear hard, while others appear soft. To recreate these characteristics in
the 3-D world, we apply a "material" to an object which tells Blender how to render the object's color, how
shiny the object should appear, its perceived "hardness" and other properties (Figure 3-14).
Textures
Take a look at the things around you again. Besides their material properties, the things around you also have
texture. Texture affects not only how something feels (smooth or rough), but also how something looks
(colors and patterns). Since we can't touch what we make in the 3-D CGI world, we will focus on how things
look.
Image maps
A common method for applying textures is through the use of image maps. That is 2-D images which we then
"wrap" around an object (see Figure 3-15).. Image maps allow us to represent minute detail on our models
(objects) that would be difficult to model directly and that would greatly increase the number of polygons if
we did model them. Using image maps lets us keep the number of polygons low on our models, thus letting
Blender render our scenes faster, which is especially important for real-time rendering in the game engine.
UV mapping
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Introduction to 3D
UV mapping
One common problem with image maps is the accurate wrapping of the maps around an object, especially a
complex one. Many times the texture will not be aligned as we wish or it may "stretch" (Figure 3-16). A
popular method for overcoming this problem is the use of UV mapping.
UV vs. XY coordinates
In order to continue, it is necessary to point out what UV coordinates are. As mentioned in the 3-D overview,
you can describe a point (vertex) by giving its X, Y and Z coordinates. If you want to 'map' a 2-D image onto
a 3-D object, the XYZ coordinates have to be transformed into two dimensions. These transformed
coordinates are usually called the "UV coordinates". Instead of calculating UV coordinates automatically, you
can define them yourself in Blender. This means, that for each vertex, not only a an XYZ coordinate is stored,
but also the two values for U and V.
So, how does UV mapping work? Take a look at the head object in Figure 3-17. Each corner of the faces is a
vertex, and each vertex has an XYZ and UV coordinate as explained earlier. Using Blender's UV editor, we
unwrap the mesh, much like we do when we take a globe and lay it flat to make a map of the world, and lay
that mesh on top of our 2-D image texture.
Then, by moving the unwrapped mesh's UV coordinates, we can tell Blender exactly where the texture should
go when Blender wraps the texture around our 3-D object (Figure 3-18).
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20
Introduction to 3D UV vs. XY coordinates
The reason it is called a UV editor and not a UVW editor, is that we make our adjustments in 2-D (UV) and
Blender automatically takes care of the W coordinate when it wraps the texture around our model. Not having
to worry about the third dimension makes our job easier in this case.
Viewing 3-D space
To do anything in 3-D, we need to be able to see what we are doing. This is accomplished using "views". This
section will discuss the various views available in Blender ("standard", "interactive" and "camera" views), and
the two view modes available. This section will not cover the steps you need to take to use the views. Those
will be explained in Section 4.10. It will also mention the use of lights, which are not actually views but are
necessary if you want to see anything when you render your 3-D scene and can be used to alter the mood of
our scenes.
Standard
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There are six pre-programmed standard views in Blender, each looking along a particular axis as shown in
Figure 3-19. These views are generally used when modeling objects because they help to provide a sense of
orientation. They are also useful if you get disoriented using the interactive view.
Interactive (free)
While the standard views are very useful for modeling, sometimes they don't help us visualize how an object
will look in 3-D (Figure 3-20). This is when Blender's interactive view becomes useful. Blender's interactive
view allows you to rotate your entire 3-D scene in any direction interactively (in real-time) to let you view
things from any angle (Figure 3-21). This helps you visualize how your scenes and models will look.
15/02/2011 12:39:15 21
Introduction to 3D
Interactive (free)
Cameras
Camera
The standard and interactive views are generally not used when it is time to render your scenes (stills,
animations or real-time rendering in the game engine). Instead, you use a camera view for rendering. You can
think of this like a movie set. You are the director and can walk around and look at your set from any
direction you want (standard and interactive views) to make sure everything is just as you want it, but when it
is time to shoot the scene you need a camera. This is what your audience will see, and the same holds true for
camera views (Figure 3-22).
View modes
Here are two viewing modes for all the views in Blender: "orthogonal" and "perspective". Orthogonal mode
views everything without perspective, whereas the perspective mode, as the name implies, uses perspective
(Figure 3-23). Orthogonal mode is useful when creating your models because there is none of the "distortion"
associated with the perspective mode, and this helps your accuracy. The perspective mode, like the interactive
view, can help give you a sense of what your model will look like, but without the need to rotate the entire
3-D scene. Rotating the entire scene can be slow if it is very complicated.
Lights
When you are ready to render your scene, or play your game, you will need at least two things: a camera and
lights. If you try to render without a camera you will get an error message, but if you try to render without a
light all you will get is a black image. This is one of the most common mistakes for new to Blender users, so
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Introduction to 3D
Lights
if you try to render something and all you get is a black square be sure to check if you've put in a lamp or not.
For the interactive 3-D graphics, there can be scenes without light, but they usually look flat.
There is more to lights than just being able to see. Just like in real life, lights can help set the atmosphere or
mood of a scene. For example, using a low blue light helps to create a "cool/cold" atmosphere, while a bright
orange light might create a "warm" one (Figure 3-24). Lights can be used to simulate ambient light, muzzle
flashes or any other effect where you would expect to see light.
Because you will be creating games with objects that move and change, there is another important concept we
must cover:
Transformations
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As touched on earlier, we describe the locations of objects in our 3-D worlds by using an origin and a XYZ
coordinate system to measure with. The coordinates calculated from this default origin are known as global
coordinates. In addition, an object's center serves as its own origin, and so the object can have its own XYZ
axes (Figure 3-25). This is called a local origin, and a local coordinate system with local coordinates. But why
is this important?
A game where nothing moves or changes will not get much of a following. The objects in your games will
need to move, and this is one place where the concept of transformations becomes important. The three most
common transformations are translation, rotation and scaling.
Transformation
Description
Translation
When an object move from point A to point B
Rotation
When an object spins around a particular point or axis
Scaling
When an object increases or decreases in size
Table 3-2.
Transformations
When you make your games, you'll have to keep in mind that transformations are relative and can affect game
play. When an object translates from point A to B in the global coordinate system, from that object's point of
view, its local coordinate system doesn't necessarily move. For example, a character standing in a moving
train seems to be stationary from their point of view. The train's speed may be 100 kph, but the character feels
like they are standing still. Their local origin (their center) doesn't move as far as they are concerned.
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23
Introduction to 3D Transformations
However, if we look at the same character from the point of view of someone standing still outside the train,
now the character is moving. From this second character's local point of view, they are standing still and the
first character is moving, but neither are rotating. Or are they?
If we look from the point of view of another character, hovering in space, not only are both of the other
characters on the Earth, rotating as the Earth rotates on its axis, but also as the Earth rotates around the Sun.
So, how does this affect game play? Imagine everyone is trying to hit a stationary target on the train. The first
character has the easiest job, a stationary target, the second character has to hit moving target, and the third
character has to hit a target that is moving and experiencing two forms of rotation.This shifting of points of
view is called "coordinate transformation", and as you can see, it can have an important impact on game play.
In most 3-D software packages you can work with these coordinate systems using so-called "hierarchies".
You can define one object as being the "parent" of another object; which then becomes a child. Now all
transformations of the parent are also applied to its children. That way you only have to define motion for a
parent to have all its children moving in the same way. In the solar system example, we humans all are in fact
"children" of the Earth, which in turn is a "child" of the Sun.
One last point that needs to mentioned is that transformation is not restricted to just shapes. Materials,
textures, and even lights can be moved, rotated and scaled. In fact, anything that exists in your 3-D world is
actually an object and so is subject to transformations. As your 3-D skills develop, you will learn how to use
global, local and relative transformations to affect game play and to create interesting effects. Now that you
have received a basic introduction to 3-D CGI, it's time to talk about game engines and aspects of good
games.
Game Engines and Aspects of a Good Game
What is a game engine?
A game engine is software that simulates a part of reality. Through a game engine, you interact with a 3-D
world in real-time, controlling objects which can interact with other objects in that world. If you have ever
played a video game on a computer, a console or in a game arcade, you have used a game engine of some
kind. The game engine is the heart of a game and consists of several parts. One part displays the 3-D world
and its objects on your screen, drawing and redrawing your scenes as things change. Another part deals with
decision making (known as game logic), for example, deciding when events like doors opening should occur.
Another part simulates physics, such as gravity, inertia, momentum and so on. Yet another part detects when
objects collide with each other, while another actually moves objects.
The game engine tries to simulate all these things as quickly as possible to provide a smooth fluid simulation.
For example, in a computer baseball game, the game engine will have the pitcher throw you a pitch (moving
an object). As the ball travels the game engine will calculate all the physics that act on the ball, such as
gravity, air resistance, etc. Then you swing the bat (or more accurately, you tell the game engine to swing the
batter's bat) and hopefully hit the ball (i.e. collision detection between the ball and bat).
This is a very simplified example, he game engines you have used are much more complicated, and can take a
team of programmers and a great deal of time to create. Or at least, that was the case until Blender's game
engine was released.
15/02/2011 12:39:15 24
Introduction to 3D Blender's game engine -- Click and drag game creation
Blender's game engine - Click and drag game creation
Blender is the first game engine that can create complete games without the need to program. Through its
click-and-drag graphical user interface (GUI), even those with no programming experience can enjoy the
challenge of creating fun and exciting games.
After you create your 3-D world and 3-D objects, you only need to use a series of pull-down menus, simple
key strokes and mouse clicks to add behavioral properties to that world and those objects and bring them to
life. For professionals, this allows for the rapid prototyping of games, and for non-professionals, it's the first
chance to produce their own games without having to spend years learning to program or the need for large
programming teams. Of course, for those who can program, Blender uses the Python scripting language to
allow programmers to extend Blender's game engine even further.
This relative ease of use, though, hides the Blender game engine's true innovation...
"True" and "fake" 3-D game engines
Blender is a "true" 3-D game engine. Until recently, game logic (decision making) wasn't done on an object
level. This meant that a "higher intelligence" (HI) in the game had to control all the objects, moving them
when appropriate or keeping track of their condition (i.e. alive or dead). With the advent of "true" 3-D game
engines, each object in a game is its own entity and reports such information back to the game engine.
For example, if you are playing a game where you walk through a maze that has hidden doors, in the past the
HI would have had to decide when you were close enough to a hidden door and then open it. With Blender's
game engine, the door itself can have a sensor function and will determine when another object is close
enough, then the door will open itself.
Another example would be a shooting game. The gun has logic attached that detects when you pull the trigger,
the gun then creates a new bullet object with a certain starting speed. The bullet, which is now its own entity,
shoots out of the gun and flies through the air all the while being affected by air resistance and gravity. The
bullet itself has sensors and logic as well, and detects whether it hits a wall or an adversary. On collision, the
logic in the bullet and the logic in the collided object define what will happen.
In the past, when you pulled the trigger, the game engine would calculate whether a bullet fired at that time
would hit the target or not. There was no actual bullet object. If the game engine determined that a hit would
have occurred, it then told the object that had been hit, how to react.
The advantage of Blender's "real" 3-D game engine is that it does a better job of simulating reality because it
allows for the randomness that occurs in the real world. It also distributes the decision load so that a single HI
isn't required to decide everything.
While Blender provides you with the technology to create good games, it doesn't create them automatically.
To create good games, you need to understand three important aspects of games.
Good games
If you analyze successful games, you will find that they have three aspects in varying degrees. This is known
as the "Toy, immersive, goal" theory of game creation.
Toy The toy aspect of a game refers to the immediate fun of just playing it. You don't need to think too much,
you can just grab the mouse or the game controller and start playing, much like you did with your toys when
you were a child. You didn't need to read a manual on how to play with your toy cars, or spend time figuring
15/02/2011 12:39:15 25
Introduction to 3D Good games
out complicated strategy. In short, games with a high degree of toy are very intuitive. Think of your favorite
arcade game at your local game arcade. Most likely you only needed one joystick and two or three buttons, or
a simple gun with a trigger.
This doesn't mean that such games don't require skill, but that you can gain immediate enjoyment
from playing them.
Immersive The "immersive" aspect of a game is the degree to which a game makes you forget you are
playing a game, sometimes called the "suspension of disbelief". Flight simulators or racing simulators are a
good example of this. Realism is an important factor in this, and is one of the reasons that simulators have
reached such an advanced level in realism. The "Mechwarrior" series and "WarBirds" are two excellent
examples of immersive games which have very realistic environments, animations and sounds. They are fairly
low on the toy aspect and take some time to learn to play, with almost every key on the keyboard used for
some function.
The old one-button joysticks have been replaced with HOTAS (Hands On Throttle And Stick)
systems consisting of a joystick with seven to ten buttons for one hand, a throttle device with an equal
number of buttons or dials for the other and even pedals for your feet. These systems combine with
the game to create an incredibly immersive environment. These games also often have a high degree
of "goal".
Goal The "goal" aspect of a game is the degree to which a game gives you a goal to achieve. This often
involves a lot of strategy and planning. "Age of Empires" and "SimCity" are two games that are very goal
oriented. Goal oriented games are often very low on the toy aspect, "SimCity" for example comes with a thick
manual explaining all the intricate details of "growing" a successful city. This is not always the case though
"Quake" is a goal oriented game which also has a good deal of toy and immersive aspects to it.
Balance When you create your games, you will have to strike a balance among the toy, immersive and goal
aspects of your games. If you can create a game that has a high degree of each aspect, you'll most likely have
a hit on your hands.
Conclusion
In this chapter you have been introduced to the basic concepts of 3-D including vertices, polygons, materials,
textures, origins, coordinate systems and transformations. You have also been introduced to what makes a
game work, both on a technological level with the discussion of game engines, and on a conceptual level with
the discussion of what makes good games good.
The rest of this book will show you how to use Blender to put these concepts to work when creating games.
Once you have finished this guide, you'll have all the tools you'll need to make games, the rest will fall to your
own creativity. Good luck and we look forward to seeing you announce your games on Blender's discussion
boards (see Appendix).
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15 26
Blender Basics
The Interface
If you are new to Blender, you should get a good grip on how to work with the user interface before you start
modelling. The concepts behind Blender's interface are specifically designed for a graphics modelling
application and the vast array of features are different and differently grouped from other 3D software
packages. In particular, Windows users will need to get used to the different way that Blender handles
controls such as button choices and mouse movements. This difference is one of Blender's great strengths.
Once you understand how to work the Blender way, you will find that you can work exceedingly quickly and
productively. Some features are familiar, like the top menu bar of "File", "Add"... "Help". However, many
other features are quite unheard of in most (if not all) other applications. For example: Blender windows
cannot overlap and hide each other, one exception being a small number of mini-floating panels which are
transparent, fold-able, small, and dock-able. Blender relies heavily on keyboard shortcuts to speed up the
work. Blender's interface is entirely drawn in OpenGL and every window can be panned, zoomed in/out, and
its content moved around.
Your screen can be organized exactly to your taste for each specialized task and this organization can be
named and memorized.
These key differences (and many others) make Blender a unique, powerful, and very nimble application, once
you take the time to understand it.
Blender's Interface Concept
The user interface is the vehicle for two-way interaction between the user and the program. The user
communicates with the program via the keyboard and the mouse, and the program gives feedback via the
windowing system. The interface can be broken down into several key areas: Windows, Contexts, Panels, and
Buttons (controls). For example, The Button Window contains Context buttons which show different groups
of Panels and the Panels each show groups of Buttons. These principal areas are discussed on the following
pages.
Keyboard and mouse
This chapter gives an overview of the general mouse and keyboard usage in Blender and the conventions used
in this Manual to describe them, as well as tips on how to use non-standard devices.
Conventions in this Manual
This manual uses the following conventions to describe user input: The mouse buttons are called LMB (left
mouse button), MMB (middle mouse button) and RMB (right mouse button). If your mouse has a wheel,
MMB refers to clicking the wheel as if it were a button, while MW means rolling the wheel.
Hotkey letters are shown in this manual like they appear on a keyboard; for example GKEY which refers to
the lowercase g. When used, the modifier SHIFT is specified just as the other modifier keys, CTRL and/or
ALT ; this gives, for example, CTRL-W or SHIFT-ALT-A. NUMPAD-0 to NUMPAD-9, NUMPAD-+ and
so on refer to the keys on the separate numeric keypad. NUMLOCK should generally be switched on.
Other keys are referred to by their names, such as ESC, TAB, Fl to F12 .
15/02/2011 12:39:15 27
Blender Basics
Of special note are the arrow keys, UP, DOWN, LEFT, RIGHT and so on.
Keyboard and mouse
General Usage
Blender's interface is designed to be best used with a three-button mouse. A mouse wheel is quite useful, but
not essential. Because Blender makes such extensive use of both mouse and keyboard, a golden rule has
evolved among Blender users: Keep one hand on the mouse and the other on the keyboard. If you normally
use a keyboard that is significantly different from the English keyboard layout, you may want to think about
changing to the English or American layout for your work with Blender. The most frequently used keys are
grouped so that they can be reached by the left hand in standard position (index finger on F) on the English
keyboard layout. This assumes that you use the mouse with your right hand.
Mouse Button Emulation
It is possible to use Blender with a two-button mouse or an Apple single-button Mouse. The missing buttons
can be emulated with key/mouse button combos. Activate this functionality in the User Preferences, View and
Controls Context, "Emulate 3 Button Mouse" button.
The following table shows the combos used:
2 buttons Mouse
Apple Mouse
LMB
LMB
LMB
MMB
Alt-LMB
Option/Alt-LMB
RMB
RMB
Command/Apple-LMB
All the Mouse/Keyboard combinations mentioned in this book can be expressed with the combos shown in
the table. For Example, SHIFT- ALT-RMB becomes SHIFT- ALT-COMMAND-LMB on a single-button
mouse.
NumPad Emulation
The Numpad keys are used quite often in Blender and are not the same keys as the regular number keys. If
you have a keyboard without a Numpad (e.g. on a laptop), you can tell Blender to treat the standard number
keys as Numpad keys in the User Preferences, System & OpenGL Context, "Emulate Numpad" button.
The Window System
When you start Blender you may see a console (text) window open and, shortly after, the main user interface
window will display. You may also see a splash screen announcing the Blender version, but it will disappear
as soon as you move your mouse.
The default Blender scene
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28
Blender Basics
The default Blender scene
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4- 1 . Blender default scene layout
The default Blender scene shows the screen you should get after starting Blender for the first time. By default
it is separated into three windows:
• The main menu at the top is the header part of a User Preferences window
• A large 3D window (3D Viewport window)
• The Buttons Window (at the bottom) These windows can be further broken down into separate areas.
As an introduction we will cover a few of the basic elements:
• Window Type: Allows you to change what kind of window it is. For example, if you want to see the
Outliner window you would click and select it.
• Main Top Menu: Is the main menu associated with the "User Preferences" window type. To actually
see the information, you need to click and drag the area between the 3D window and menu header;
Roll the mouse between them and when it changes to a up/down arrow you can drag and see the "User
Preferences" window.
• Current Screen (default is Model): By default, Blender comes with several pre-configured Screens for
you to choose from. If you need custom ones, you can create and name them.
• Current Scene: Having multiple scenes present allows for you to break up your work into organized
patterns.
• Resource Information (found in the User Preferences header): Gives you information about
application and system resources. It tells you how much memory is being consumed based on the
number of vertices, faces and objects in the selected scene. It is a nice visual check to see if you are
pushing the limits of your machine.
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Global
4-2. Blender 3D Manipulator Buttons
• 3D Transform Manipulator: Is a visual aid in transforming objects. Objects can also be transformed
(grabbed/moved - rotated - scaled) using the keyboard shortcuts : (g/r/s); CTRL SPACE will display
the manipulator pop-up. The manipulator visibility can also be toggled by clicking the "hand" icon on
the toolbar. The translation/rotation/scale manipulators can be displayed by clicking each of the three
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Blender Basics The Window Header
icons to the right of the hand icon. Shift LMB -clicking an icon will add/remove each manipulator's
visibility.
• 3D Cursor: Can have multiple functions. For example, it represents where new objects appear when
they are first created; Or it can represent where the base of a rotation will take place.
• Cube Mesh: By default, a new installation of Blender will always start with a Cube Mesh sitting in the
centre of Global 3D space. After a while, you will most likely want to change the "Default" settings;
This is done by configuring Blender as you would want it on startup and then saving it as the
"Default" using CTRL UKEY (Save Default Settings).
• Light (of type Lamp): By default, a new installation of Blender will always start with a Light source
positioned somewhere close to the centre of Global 3D space.
• Camera: By default, a new installation of Blender will always start with a Camera positioned
somewhere close to the centre of Global 3D space and facing it.
• Currently selected object: This field shows the name of the currently selected object.
• Editing Panel Group: The bottom window displays panels and those panels are grouped. This row of
buttons (called Context Buttons) allows you to select which group of panels are shown. Some buttons
will display additional buttons (called Sub-Context Buttons) to the right for selection of sub-groups or
groups within groups.
• Current frame: Blender is a modelling and animation application; As such, you can animate things
based on the concept of frames. This field shows what the current frame is.
• Viewport shading: Blender renders the 3D window using OpenGL. You can select the type of
interactive shading (called Draw Type: in the Blender shading list) that takes place by clicking this
button and selecting from a variety of shading styles. You can select from boxes all the way to
complex Textured shading. It is recommended that you have a powerful graphics card if you are
going to use the Textured style.
• Rotation/Scaling Pivot point: Allows you to select where rotation/scaling will occur. For example,
rotation could occur about the object's local origin or about the 3D Cursor's position, amongst many
others.
• Panels: Help group and organize related buttons and controls. Some panels are visible or invisible
depending on what type of object is selected.
• Layers: Make modelling and animating easier. Blender Layers are provided to help distribute your
objects into functional regions. For example, one layer many contain a water object and another layer
may contain trees, or one layer may contain cameras and lights.
• 3D Window header: All windows in Blender have a header. This is the header for the 3D window.
The Window Header
Most windows have a header (the strip with a lighter grey background containing icon buttons). We will also
refer to the header as the window ToolBar. If present, the header may be at the top (as with the Buttons
Window) or the bottom (as with the 3D Window) of a window's area.
Sample Window Headers using the Default Theme
J# '\ » View Salstl Object |^,0bjet1 Mode j] \0 -\ fi -j:
;|K»|o|g,^ -,r I I IIIHIvllll
'|g i T? Panels © [ I ^|t£ {
3KiaA@ 1
ba 7 View Select Martyr curve |.^*jtCQUie:l
*| |/|;|ip-oeipe IxIfIUlIaIH-IIAI
Blender is themeable, for this book we use the default theme which is default for a new Blender installation.
When you move the mouse over a window, its header changes to a lighter shade of grey. This means that it is
"focused"; All hotkeys you press will now affect (only) the contents of this window.
The icon at the left end of a header, with a click of the LMB , allows selection of one of 1 6 different window
types. Most Window Headers, located immediately next to this first "Window Type" Menu button, exhibit a
15/02/2011 12:39:15 30
Blender Basics Changing Window Frames
set of menus. Menus allow you to directly access many features and commands. Menus can be hidden and
shown via the triangular button next to them.
Changing Window Frames
You can maximize a window to fill the whole screen with the "View>Maximize Window" menu entry. To
return to normal size, use the "View->Tile Window". A quicker way to achieve this is to use SHIFT-SPACE,
CTRL-UP or CTRL-DOWN to toggle between maximized and framed windows.
You can change the size of a window frame by focusing the window you want to split (moving the mouse to
its edge), clicking the vertical or horizontal border with MMB or RMB , and selecting "Split Area". You can
now set the new border's position by moving your mouse to the desired position, and clicking with LMB; or
you can cancel your action by pressing ESC. The new window will start as a clone of the window you split. It
can then be set to a different window type, or to display the scene from a different point of view (in the case of
the 3D View).
Join Area
No Heade
□
4-6. The Split Menu
You can resize windows by dragging their borders with LMB.
You can join two windows into one by clicking a border between two windows with MMB or RMB and
choosing "Join Areas". Then you'll be prompted to click on one of the two windows an arrow will be drawn to
visualize which windows will be closed; the one you click will disappear, while the other will be expanded to
cover the full area of both windows. If you press Esc before clicking on one of the windows, the operation
will be aborted.
Console Window & Error Messages
The Console Window is an operating system text window that displays messages about Blender operations,
status, and internal errors. If Blender crashes on you, it is a good idea to check the Console Window for clues.
When Blender is started on a Microsoft Windows OS; The Console Window is first created as a separate
window on the desktop, then assuming the right conditions are met, the main Blender Application window
should also appear.
The Blender Console Window must remain open while Blender is executing; If the Blender Console Window
is closed then the Blender Application window will also close, and any unsaved Blender work will be lost!
The Blender Console Window may not be visible, some reasons for this are:
• The Blender Application window may be covering the Console Window. If this is the case just use the
Windows task bar to click on the Blender Console Window icon, which should make the Blender
Console Window visible.
• The Blender Console Window may be minimized/iconifed when Blender starts. If this is the case
again, just use the Windows task bar to click on the Blender Console Window icon, which should
make the Blender Console Window visible.
15/02/2011 12:39:15 31
Blender Basics
Console Window running Linux
Console Window & Error Messages
The Blender Console Window in Linux will generally only be visible on the Desktop if Blender is started
from a Linux Terminal/Console Window, as Blender uses the Console Window it is started in to display it's
Blender Console output.
Most of the different Linux distributions have Blender as one of their applications you can install from their
packaging systems. When Blender is installed in this way an icon is usually also installed into their menu
systems; Allowing for Blender to be started by clicking an icon rather than having to open a separate Linux
Console/Terminal window and start Blender from there; When Blender is started using an icon rather than
being started from a Terminal window, the Blender Console Window text will most likely be hidden on the
Terminal that the X Window System was started from or in the system console log.
Console Window running Mac OS X
On Mac OS X you also can start Blender from a Terminal to see the output of Blender. However if you start
Blender from the finder the console window is hidden. To see the output start the "Console" application, this
works for all applications which do outputs to the console.
Window types
Wndaw type:
% Scripts Window
File Browser
Image Browser
% Nods Editor
§ Buttons Window
™= Oiilliner
i User Preterarieas
i! Texl Editor
V Audio Window
C;) Timeline
S Video Sequence Editor
d UWImage Editor
5r NLA Editor
X Aclion Editor
fy Ipo Curve Editor
^3D View
1 View Salad Objs
□
4-7. The Window Type selection menu
The Blender interface, the rectangular window provided by your operating system, is divided up into many
rectangular window frames. Each window frame may contain different types of information, depending upon
the Window type.
Each window frame operates independently of the others, and you can have the same type of window in many
frames. For example, you may have several 3D windows open but each looking at the scene from a different
perspective. You can split and merge and resize window frames to suit whatever you are working on. You can
also arrange some window frames to show with or without a header to save screen space.
Window types are broken up by functionality:
15/02/2011 12:39:15
32
Blender Basics Window types
• Scripts window user interface for running Python scripts that extend Blender
• File Browser for storage and retrieval, especially of .blend files
• Image Browser search your computer for images, seen as thumbnails
• Node Editor - process/enhance images and materials
• Buttons Window - panels that configure objects and set/select options
• Outliner - Helps you find and organize your objects.
• User Preferences - customize Blender to your work style and computer
• Text Editor - keep notes and documentation about your project, and write Python scripts.
• Audio Window - see sound files and correlate them to frames
• Timeline - jump to different times (frames) in your animation
• Video Sequence Editor - assemble video sequences into a film strip
• UV/Image Editor - edit and paint pictures
• NLA Editor - manage non-linear animation action strips
• Action Editor - combine individual actions into action sequences
• Ipo Curve Editor - make things move or change
• 3D View - graphical view of your scene
You can select the Window type by clicking the window's header leftmost button. A pop-up menu displays
showing the available Window types. The tutorials will cover the window types needed for this book.
Button Window Contexts
The Button Window shows six main Contexts, which can be chosen via the first icon row in the header
(Contexts and Sub-Contexts Example). Each of these might be subdivided into a variable number of
sub-contexts, which can be chosen via the second icon row in the header (Contexts and Sub-Contexts
Example), or cycled through by pressing the same Context button again:
Contexts Sub-contests
^ Panels
g|^|P|a| M*|a|w|a
□
4-8. Contexts and Sub-Contexts Example
• Q 1 Logic (F4) - Switches to Logic context.
• H Script - No shortcut. Switches to Script context.
♦ 9 Shading (F5) - Switches to Shading context.
♦ & Lamp - No shortcut.
♦ *i Material - No shortcut.
♦ a Texture - Shortcut F6.
• ^* Radiosity - No shortcut.
• If World- Shortcut F8.
• tt Object (F7) - Switches to Object context.
♦ It Object - No shortcut.
♦ If Physics - No shortcut.
♦ Q Editing (F9) - Switches to Editing context.
• S Scene (F10) - Switches to Scene context.
♦ H Rendering - No shortcut.
♦ J5 Anim/Playback - No shortcut.
♦ V Sound - No shortcut.
Once the Contexts is selected by the user, the sub-context is usually determined by Blender on the basis of the
active Object. For example, with the Shading context, if a Lamp Object is selected then the sub-context shows
Lamp Buttons. If a Mesh or other renderable Object is selected, then Material Buttons is the active
15/02/2011 12:39:15 33
Blender Basics Button Window Contexts
sub-context, and if a Camera is selected the active sub-context is World.
The Buttons in each context are grouped into Panels.
The menu of available options, shown in a window's header, may change depending on the mode of that
window. For example, in the 3D View window, the Object menu in Object mode changes to a Mesh
operations menu in Edit mode, and a paint menu in Vertex Paint mode. If you are reading this manual and
some menu option is referenced that does not appear on your screen, it may be that you are not in the proper
mode, or context, for that option to be valid.
Menus
Blender contains many menus each of which is accessible from either the window headers or directly at the
mouse's location using hotkeys.
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□
Blender Toolbox Menu Layout
For example, you can access the Toolbox in the 3D window using either the mouse or the keyboard. From the
keyboard you would use the SPACE. To access it using the mouse just hold down the LMB or RMB buttons
for a few seconds and the Toolbox will pop-up.
Some menus are context sensitive in that they are only available under certain situations. For example, the
Booleans menu is only available in Object Mode using the WKEY. The same hotkey (WKEY) in Edit Mode
brings up the Specials menu.
While you are using Blender be aware of what mode and types of object are selected. This helps in knowing
what hotkeys work at what times.
Panels
Panels generally appear in the Buttons window and by default the Buttons window is at the bottom. The
Buttons window includes the Button window header and panels.
15/02/2011 12:39:15
34
Blender Basics
[| g ; ) ' Panels a I"-:!; J;VLffiH| f i
Panels
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□
4-26. A Blender Panel
Each button on the Buttons header groups panels together into what is called a Context. And those Contexts
are grouped further into Sub-Contexts. For example, all Material panels are grouped under the Shading
context and Material sub-context.
The panels are not fixed in position relative to the window. They can be moved around the window by LMB
clicking and dragging on the respective panel header.
Panels can be aligned by RMB on the Buttons Window and choosing the desired layout from the Menu which
appears. Using MW scrolls the Panels in their aligned direction and CTRL-MW and Ctrl-MMB zooms the
Panels in and out. Single Panels can be collapsed/expanded by LMB clicking the triangle on the left side of
their header.
Particularly complex Panels are organized in Tabs. Clicking LMB on a Tab in the Panel header changes the
buttons shown in. Tabs can be "torn out" of a Panel to form independent panels by clicking LMB on their
header and dragging them out. In a similar way separate Panels can be turned into a single Panel with Tabs by
dropping one Panel's header into another.
Buttons and Controls
Buttons are mostly grouped in the Button Window. But they can appear in other Windows.
RENDER
□
4-27. An Operation Button
These are buttons that perform an operation when they are clicked (with LMB, as all buttons). They can be
identified by their brownish color in the default Blender scheme (An operation button).
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Hard | Ray Mi
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□
4-28. Toggle Buttons
Toggle buttons come in various sizes and colors. The colors green, violet, and grey do not change
functionality, they just help the eye to group the buttons and recognize the contents of the interface more
quickly. Clicking this type of button does not perform any operation, but only toggles a state.
Some buttons also have a third state that is identified by the text turning yellow (the Emit button in Toggle
buttons). Usually the third state means "negative," and the normal "on" state means "positive."
15/02/2011 12:39:15
35
Blender Basics Buttons and Controls
Radio buttons are particular groups of mutually exclusive Toggle buttons. No more than one Radio Button in
a given group can be "on" at one time.
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□
4-29. Number Buttons
Number buttons can be identified by their captions, which contain a colon followed by a number. Number
buttons are handled in several ways: To increase the value, click LMB on the right of the button, where the
small triangle is shown; to decrease it, click on the left of the button, where another triangle is shown.
To change the value in a wider range, hold down LMB and drag the mouse to the left or right. If you hold
CTRL while doing this, the value is changed in discrete steps; if you hold SHIFT, you'll have finer control
over the values. ENTER can be used in place of LMB here.
You can enter a value directly by holding SHIFT and clicking LMB. You can also enter simple equations, like
"3*2" instead of 6. Handy geometric constants to remember: pi is "3.14" and the square root of two is "1.414".
Press SHIFT-BACKSPACE to clear the value; SHIFT-LEFT ARROW to move the cursor to the beginning;
and SHIFT-RIGHT ARROW to move the cursor to the end. Press ESC to restore the original value.
Some number buttons contain a slider rather than just a number with side triangles. The same method of
operation applies, except that single LMB clicks must be performed on the left or on the right of the slider,
while clicking on the label or the number automatically enters keyboard input mode.
Use the Menu buttons to choose from dynamically created lists. Menu buttons are principally used to link
Data Blocks to each other. (Data Blocks are structures like Meshes, Objects, Materials, Textures, and so on;
by linking a Material to an Object, you assign it.)
□
4-30. Datablock Link Buttons
1 . The first button (with the tiny up and down pointing triangles) opens a menu that lets you select the
Data Block to link to by holding down LMB and releasing it over the requested item.
2. The second button displays the type and name of the linked Data Block and lets you edit its name
after clicking LMB.
3. The "X" button clears the link.
4. The "car" button generates an automatic name for the Data Block.
5. And the "F" button specifies whether the Data Block should be saved in the file even if it is unused
(unlinked).
Unlinked data is not lost until you quit Blender. This is a powerful Undo feature, if you delete an object the
material assigned to it becomes unlinked, but is still there! You just have to re-link it to another object or press
the "F" button.
15/02/2011 12:39:15 36
Blender Basics
Color Selector
Color Selector
Some controls pop-up a dialog panel. For example, Color controls, when clicked, will pop up a Color Selector
dialog.
4-31. Color Selector Panel
Screens
Blender's flexibility with windows lets you create customized working environments for different tasks, such
as modelling, animating, and scripting. It is often useful to quickly switch between different environments
within the same file. For each Scene, you need to set the stage by modelling the props, dressing them and
painting them through materials, etc. In the example picture in Window system, we are in the modelling stage.
S|SR:Z-Model
ADD NEW
1 -Animation
2-Model
3-Material
4-Sequence
5-Scripting
□
4-32. Screen Layout Selection Menu
To do each of these major creative steps, Blender has a set of pre-defined screens, or window layouts, that
show you the types of windows you need to get the job done quickly and efficiently:
1-Animation Making actors and other objects move about.
2-Model Creating actors, props, and other objects.
3-Material Painting and texturing surfaces.
4-Sequence Editing scenes into a movie.
5-Scripting Documenting your work, and writing custom animations.
Blender sorts these screen layouts for you automatically in alphabetical order. (A screen name typically starts
with a number, which controls the alphabetical order) The list is available via the SCR Menu Buttons in the
User Preferences Window header shown in (Screen and Scene selectors). To change to the next screen
alphabetically press Ctrl-RIGHT ARROW; to change to the previous screen alphabetically, press
CTRL-LEFTARROW
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37
Blender Basics Screens
Screen selector Scene selector
r |sCR:g-Model fx] 7 \ SCE:Scene (~X~|
□
4-33. Screen Selector and Scene Selector Dropdown Menus
By default, each screen layout 'remembers' the last scene it was used on. Selecting a different layout will
switch to the layout and jump to that scene.
All changes to windows, as described in Window system and Window types, are saved within one screen. If
you change your windows in one screen, other screens won't be affected, but the scene you are working on
stays the same in all screens.
Adding a new Screen
As you scroll through the Screen list, you will see that one of the options is to Add New - namely, add a new
window layout. Click and select ADD NEW. When you click this, a new frame layout is created based on
your current layout.
- SR:2-Moclel
pass
ixj
w 1 -Animation
2-Model
3- Materia!
4-Sequence
5-Scripting
□
4-34. Screen Selector ADD NEW Selected
Give the new screen a name that starts with a number so that you can predictably scroll to it using the arrow
keys. You can rename the layout by LMB into the field and typing a new name, or clicking again to position
the cursor in the field to edit. For example you could use the name "6-MyScreen".
Deleting a Screen
You can delete a screen by using the Delete Data Block button and confirm by clicking Delete current screen
in the pop-up dialog box.
Use the window controls to move frame borders, split and consolidate windows. When you have a layout you
like, Ctrl-U to update your User defaults. The buttons window has a special option, if you RMB on its
background, to arrange its panels horizontally across or vertically up and down.
Scenes
It is possible to have several scenes within the same Blender file. Scenes may use one another's objects or be
completely separate from one another. You can select and create scenes with the SCE menu buttons in the
User Preferences Window header (usually on top of the screen, also containing the menu bar). For games and
other real time content scenes have a important meaning, with scenes you can separate menus, overlays
(HUDs, scores etc.), backgrounds from the main scene by layering multiple scenes.
15/02/2011 12:39:15 38
Blender Basics Scenes
Screen selector Scene selector
T |sCR:£-Model |~x| T | SCE:Scene fx]
□
4-35. Scene Selector
Adding a new Scene
You can add a new scene by clicking the scene menu and selecting ADD NEW. When you create a new
scene, you can choose between four options to control its contents (Add Scene menu):
Add scire
Empty
Link Objects
Link ObData
Full Copy
□
4-36. Add Scene Menu
• Empty creates an empty scene.
• Link Objects creates the new scene with the same contents as the currently selected scene. Changes in
one scene will also modify the other.
• Link ObData creates the new scene based on the currently selected scene, with links to the same
meshes, materials, and so on. This means that you can change objects' positions and related
properties, but modifications to the meshes, materials, and so on will also affect other scenes unless
you manually make single-user copies.
• Full Copy creates a fully independent scene with copies of the currently selected scene's contents.
Deleting a Scene
You can delete a scene by using the Delete Data Block button "X" and confirm by clicking "Delete current
scene" in the pop dialog box.
User Preferences
The User Preferences window is where you customize and control Blender. By default this window is located
at the top and only the header is visible.
□
4-37. User Preferences window.
To see all of the User Preferences window and its content you need to drag it into view. You can do this by
moving the mouse onto the bottom edge of the Info header, or the top of the 3D window, and click the LMB
and drag downwards.
15/02/2011 12:39:15
39
Blender Basics User Preferences
When viewing all of the Info window you can start to customize Blender to fit your personality or machine
capabilities. For example, you may not like the default theme and switch to the Rounded theme. It is also
important to configure the paths to enable automatically backup [save].
Navigating in 3D
Blender is a 3D program, so we need to be able to navigate in 3D space. This is a problem because our screens
are only 2D. The 3D Views are in fact "windows" to the 3D world created inside Blender.
Using the keyboard to change your view
Place your mouse pointer over the big window on the standard Blender screen. This is a 3D View used for
showing and manipulating your 3D-worlds.
Remember that the window with the mouse pointer located over it (no click needed) is the active window!
This means that only this window will respond to your key presses.
Pressing PAD1 (the number "1" key on the numeric pad) gives you a view from the front of the scene. In the
default Blender scene, installed when you first start Blender, you will now be looking at the edge of a plane
with the camera positioned in front of it. With holding the CTRL key (on some systems also SHIFT is
possible), you can get the opposite view, which in this case is the view from the back (CTRL-PAD 1).
PAD7 returns you to the view from the top. Now use the PAD+ and PAD- to zoom in and out. PAD3 gives
you a side view of the scene.
PADO switches to a camera-view of the scene. In the standard scene you only see the edge of the plane
because it is at the same height as the camera.
PAD/ only shows selected objects; all other objects are hidden. PAD. (period) zooms to the extent of the
selected objects.
Switch with PAD7 back to a top view, or load the standard scene with CTRL-X. Now, press PAD4 four times,
and then PAD2 four times. You are now looking from the left above and down onto the scene. The 'cross' of
keys PAD8, PAD6, PAD2 and PAD4 are used to rotate the actual view. If you use these keys together with
SHIFT, you can drag the view. Pressing PAD5 switches between a perspective view and an orthogonal view.
Use CTRL-X followed by ENTER to get a fresh Blender scene. But remember, this action will discard all
changes you have made!
You should now try experimenting a little bit with these keys to get a feel for their operation and function.
Using the mouse to change your view
The main button for navigating with the mouse in the 3D View is the middle mouse button (MMB). Press and
hold the MMB in a 3D View, and then drag the mouse. The view is rotated with the movement of your
mouse. Try using a perspective view (PAD5) while experimenting — it gives a very realistic impression of 3D.
With the SHIFT key, the above procedure translates the view. With CTRL, it zooms the view.
15/02/2011 12:39:15 40
Blender Basics Using the mouse to change your view
Also explore the View-menu, here you can also change views and control other aspects of the view.
Selecting of Objects
Selecting an object is achieved by clicking the object using the right mouse button (RMB).
This operation also de-selects all other objects. To extend the selection to more than one object, hold down
SHIFT while clicking. Selected objects will change the color to purple in the wireframe view or an purple
outline is drawn around shaded objects. The last selected object is colored a lighter purple and it is the active
object. Operations that are only useful for one object, or need one object as reference, always work with the
active object.
Objects can also selected with a "border'. Press BKEY to action this, and then draw a rectangle around the
objects. Drawing the rectangle with the LMB selects objects; drawing with RMB deselects them.
Only one Object can be active at any time, e.g. to allow visualization of data in buttons. The active and
selected Object is displayed in a lighter color than other selected Objects. The name of the active Object is
displayed in the lower left corner of the 3D View. The last Object selected (or deselected) then becomes the
active Object.
Copying and linking
Blender uses a object oriented structure to store and manipulate the objects and data. This will affect the work
with Blender in many places. For example, the copying of objects or the use of Blender Materials.
In this structure an object can have its own data (in case of the Blender Game Engine Polygon-Meshes) or
share this Mesh with more other objects.
So what is the advantage of that system?
1. Reduced size of the scene in memory, on disk or for publishing on the web
2. Changes on the ObData inherits to all Objects on the same time. Imagine you decide to change a
house objects you have 100 times in your scene or changing the Material properties of one wall
3. You can design the logic and gameplay with simple place-holder objects and later swap them against
the finished objects with a click of the mouse
4. The shape of objects (the Mesh Data) is changeable at runtime of the game without affecting the
object or its position itself
Copy
The copy operation you are familiar with from other applications makes a true duplicate of the selected
objects. Copying is done fastest with the key command SHIFT-D or also with the "Duplicate" entry in the
Object-menu.
Linked Copy
A linked copy is achieved by using the ALT-D key command. Unlike copying with SHIFT-D, the mesh
forming the object is not duplicated, but rather linked to the new objects.
15/02/2011 12:39:15 41
Blender Basics
Data Browse Button
Data Browse Button
w
ME: Cube
3
F
OBCube
□
4-37. User Preferences window.
Another common method to create and change links and Blender interface element is the User Button . This
Menu Button allows to change links by pressing and holding the left mouse on it and choose a link from the
appearing menu. If there are more possibilities than the Menu can hold, a Data Browse Window is opened
instead.
If an Object has more than one user, the User Button will be blue and a number indicates the number of users
(in the above image three). Selecting this number will make a copy of the Data and makes the object "Single
User".
Linking
To link Data from the active to the selected Objects can be done with the key command CTRL-L. A menu
will ask what data you want to link. This way you can choose to link the objects between scenes, or link Ipos
(animation curves), MeshData or Materials.
□
4-39. Make Links Selection Menu.
4-40. OOPS Schematic Diagram.
The object-structure created by copy or linking actions can be visualized in the Oops Window. Call the
Outliner SHIFT-F9, then use "View->Show Oops Schematic". Here, the object "Cube" was copied two times
with ALT-D, you can see that all three objects (Blender automatically generates unique names by appending
numbers) are linked to the same Mesh Data "Cube". The object "Cube.002" was copied with SHIFT-D
resulting in two objects with their own MeshData.
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42
Blender Basics Manipulating Objects
Manipulating Objects
Most used actions in Blender involve moving, rotating, or changing the size of certain items. Blender offers a
wide range of options for doing this. See the 3DWindow section for a fully comprehensive list. The options
are summarized here.
Grab
GKEY, Grab mode. Move the mouse to translate the selected items, then press LMB or ENTER or SPACE to
assign the new location. Press ESC or RMB to cancel. Translation is always corrected for the view.
Use the middle mouse button to limit translation to the X, Y or Z axis. Blender determines which axis to use,
based on the already initiated movement.
RMB and hold-move. This option allows you to select an Object and immediately start Grab mode.
Rotate
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□
4-41. Pivot mode selection menu.
RKEY, Rotation mode. Move the mouse around the rotation centre, then press LMB or ENTER or SPACE to
assign the rotation. Press ESC to cancel. Rotation is always perpendicular to the view. Use XKEY, YKEY or
ZKEY to use the global axis for rotation or press the keys two times to rotate around the local object axis.
The centre of rotation is determined with the "Pivot"-menu in the 3D View header.
Scaling
SKEY, Scaling mode. Move the mouse from the rotation centre outwards, then press LMB or ENTER or
SPACE to assign the scaling. Use the MMB toggle to limit scaling to the X, Y or Z axis. Blender determines
the appropriate axis based on the direction of the movement.
The centre of scaling is determined by the Pivot-menu in the 3D View header (see the explanation for the
rotation).
Transform Properties
15/02/2011 12:39:15 43
Blender Basics
Transform Properties
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□
4-42. Transform Properties Panel.
To input exact values, you can call up the Transform Properties with NKEY. SHIFT-LMB -click to change the
buttons to an input field and then enter the number.
Edit Mode
Mode:
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& Vertex Paint
# Sculpt Mode
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□
4-43. Blender Mode Selection menu.
You can work with Blender Objects in two modes: Object Mode and Edit Mode. Operations in Object Mode
affect whole objects, and operations in Edit Mode affect only the geometry of an object, but not its global
properties such as location or rotation. You switch between these two modes with the TAB key or the
Mode-menu in the 3D View header.
Edit Mode only works on one object at a time, the active object. An object outside Edit Mode (i.e. Object
Mode) is drawn in purple in the 3D Windows (in wireframe mode) when selected, black otherwise.
□
4-44. Cube in Edit Mode.
In Edit Mode each vertex is drawn in purple, each edge is drawn in black and each face is drawn in translucent
dark-blue. Each selected vertex is highlighted in yellow. You can also see a grey shaded face, this is the active
face, important for UV texturing.
If multiple objects are selected and Edit Mode is entered then the last Object selected (the Active Object)
enters Edit Mode. The other Objects remain purple and in Object Mode.
If enough vertices are selected to form a face then that face is highlighted in translucent purple while the
remaining faces are highlighted in translucent dark-blue. This helps give you a frame of reference when
selecting vertices, edges or faces. The translucent effect indicates that you have selected enough vertices to
imply one or more faces. See Edge and Face Tools for further details on implicit selections.
15/02/2011 12:39:15
44
Blender Basics
Edit Mode
If the Buttons Window is visible and Editing (F9) is activated then two panels appear while in Edit Mode
(Mesh Tools and Mesh Tools More):
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□
4-45. Mesh Tools Panels.
By default the buttons (Draw Faces and Draw Edges) are pre-selected and any selected edges and faces are
highlighted.
Vertices, Edges and Faces
In basic meshes, everything is built from three basic structures: Vertices, Edges and Faces. We are not talking
about Curves, NURBS, and so forth here as they are currently not supported in the game engine. But there is
no need to be disappointed: This simplicity still provides us with a wealth of possibilities that will be the
foundation for all our models.
You can convert all Blender Object types down to a Mesh using ALT-C
Vertices
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□
4-46. Vertice examples.
A vertex is primarily a single point or position in 3D space. It is usually invisible in rendering and in Object
Mode. Don't mistake the centre point of an object for a vertex. It looks similar, but it's bigger and you can't
select it. The image shows the centre point labeled as "A". "B" and "C" are vertices.
15/02/2011 12:39:15
45
Blender Basics Vertices, Edges and Faces
To create a new vertex, change to Edit mode, hold down CTRL, and click with the LMB. Of course, as a
computer screen is two-dimensional, Blender can't determine all three vertex coordinates from one mouse
click, so the new vertex is placed at the depth of the 3D cursor 'into' the screen. Any vertices selected
previously are automatically connected to the new one with an edge. Vertex labeled "C" is a new vertex added
to the cube with a new edge (B to C)
Edges
An edge always connects two vertices with a straight line. The edges are the 'wires' you see when you look at
a mesh in wireframe view. They are usually invisible on the rendered image. They are used to construct faces.
Create an edge by selecting two vertices and pressing F.
Faces
A Face is the highest level structure in a mesh. Faces are used to build the actual surface of the object. They
are what you see when you render the mesh. A Face is defined as the area between either three (triangle) or
four vertices (quad), with an Edge on every side. Triangles always work well, because they are always flat and
easy to calculate.
Take care when using four-sided faces (quads), because internally they are simply divided into two triangles
each. Four-sided faces only work well if the Face is pretty much flat (all points lie within one imaginary
plane) and convex (the angle at no corner is greater than or equal to 180 degrees). This is the case with the
faces of a cube, for example. That's why you can't see any diagonals in its wireframe model, because they
would divide each square face into two triangles.
While you could build a cube with triangular faces, it would just look more confusing in Edit mode. An area
between three or four vertices, outlined by Edges, doesn't have to be a face. If this area does not contain a
face, it will simply be transparent or non-existent in the rendered image. To create a face, select three or four
suitable vertices and press F.
Vertex, Edge and Face Modes
In Edit Mode there are three different selection modes, Vertices, Edges or Faces. The mode can be chosen
with CTRL-TAB and using the "Select-Mode"-menu or with the icons in the 3D View header.
Select Mode
Edges
Faces
□
Select mode menu
4 / A
U
Select mode buttons
Vertices
The selected vertices are drawn in yellow and unselected vertices are drawn in a pink color.
Edges
In this mode the vertices are not drawn. Instead the selected edges are drawn in yellow and unselected
edges are drawn in a black color.
15/02/2011 12:39:15 46
Blender Basics Vertex, Edge and Face Modes
Faces
In this mode the faces are drawn with a selection handle in the middle which is used for selecting a
face. Selected faces are drawn in yellow with the selection point in orange, unselected faces are drawn
in black.
Almost all modification tools are available in all three modes. So you can Rotate, Scale and Extrude etc. in all
modes. Of course rotating and scaling a single vertex will not do anything useful, so some tools are more or
less applicable in some modes.
Basic Editing
Most simple operations from Object mode (like selecting, moving, rotating, and scaling) work the same way
on vertices as they do on objects. Thus, you can learn how to handle basic Edit mode operations very quickly.
The only notable difference is a new scaling option, Alt S which scales the selected vertices along the
direction of the normals (shrinks-fattens). The truncated pyramid shown here, for example, was created with
the following steps:
• Add a cube to an empty scene. If not in Edit mode then use TAB to enter Edit Mode.
• Make sure all vertices are deselected (purple). Use border select (BKEY) to select the upper four
vertices.
• Check that the scaling centre is set to anything but the 3D cursor, then switch to scale mode (SKEY),
reduce the size, and confirm with LMB.
• Exit Edit Mode by pressing TAB.
All operations in Edit mode are ultimately performed on the vertices; the connected edges and faces
automatically adapt, as they depend on the vertices' positions. To select an edge, you must select the two
endpoints or place the mouse on the edge and press ALT-RMB. To select a face, each corner must be selected.
Edit mode operations are many, and most are summarized in the Editing Context Buttons window, accessed
via the Q header button or via F9 (Edit Context).
Specials
With WKEY you can call up the Specials menu in Edit mode. With this menu you can quickly access
functions which are frequently required for polygon-modelling.
15/02/2011 12:39:15 47
Blender Basics
I" "in mini imimiiminim
Specials
Subdivide
Subdivide Multi
Subdivide Multi Fractal
Subdivide Smooth
Merge
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Hide
Reveal
Seiect Swap
Flip Normals
Smooth
Bevel
Set Smooth
Set Solid
Blend From Shape
Propagate To All Shapes
Select Vertex Path
Specials
Subdivide
Each selected edge is split in two, new vertices are created at middle points, and faces are split too, if
necessary.
Subdivide Multi
This is identical to Subdivide except a dialog pops up asking for the number of cuts or repeated
subdivisioning. The default is "2".
Subdivide Multi Fractal
As above, but new vertices are randomly displaced within a user-defined range.
Subdivide Smooth
Same as Subdivide, but new vertices are displaced towards the barycentre (centre of mass) of the
connected vertices.
Merge
Merges selected vertices into a single one, at the barycentre position or at the 3D cursor position.
Remove Doubles
Merges all of the selected vertices whose relative distance is below a given threshold (0.001 by
default).
Hide
Hides selected vertices.
Reveal
Shows hidden vertices.
Select Swap
All selected vertices become unselected and vice-versa.
Flip Normals
Change the Normal directions of the selected faces.
Smooth
Smooths out a mesh by moving each vertex towards the barycentre of the linked vertices.
Bevel
Bevels the entire object regardless of the selected vertices, edges or faces.
Set Smooth
Changes the selected faces to smoothing shading.
Set Solid
Changes the selected faces to faceted or flat shading.
Blend From Shape
Mixes between two shape keys
Propagate To All Shapes
Copies the changes to all shape keys
15/02/2011 12:39:15
48
Blender Basics Specials
Select Vertex Path
Select a path of vertices between two selected vertices
You can access the entries in a Popup-menu by using the corresponding numberkey. For example, pressing
WKEY and then 1KEY will subdivide the selected edges without you having to touch the mouse at all.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15 49
Pumpkin Run - Playing with 3D game technology
□
Using the "Pumpkin-Run" example file, most of the core techniques for making a 3-D game will be explained
and illustrated. However, we can't make you a professional game designer in a few pages, or even with a
complete book. But you can learn the basics here and have fun at the same time! You are also encouraged to
experiment and play with Blender.
Things you will learn here:
• Loading and saving Blender scenes
• Manipulating objects and navigating in the scene
• Basic Texture mapping
• Playing interactive 3-D in Blenders integrated 3-D engine
• Adding interactivity to control game elements
• Camera control and lights
• Object animation
• Adding and using sound
And there is more! Many things will be covered in later chapters. But don't despair the most important thing is
the gameplay. Even technically simple games can be entertaining for long times ("Tetris" for example). So
concentrate on making the game fun for others or just enjoy creating stuff yourself!
Modeling an environment
Start Blender by clicking its Icon. Blender will start with its default scene as shown in Figure [p-01].
Depending on your installation, screen display ratio and how you installed Blender there may be some slightly
differences or a splash-screen will appear.
15/02/2011 12:39:15 50
Pumpkin Run - Playing with 3D game technology
Modeling an environment
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□
Figure [p-01]. Blender just after starting it
The big window is the 3D View, our window to the world of 3D inside Blender scenes. The pink square is a
cube, we are currently looking onto the scene from above, a so called "Top View". The line drawn object to
the lower right of the cube is the representation of a Blender Camera. The object right of the cube is a light
source.
□
Blenders Camera
Now move your mouse cursor over the Camera and press your right mouse button, this selects the Camera
which is now drawn pink. The colored arrows are so called 3D-handles, by dragging them with the left mouse
button you can move the selected object along one axis.
Blender uses the right mouse button (RMB) for selecting objects!
Now we will change the view of the scene. Move the mouse cursor into the big 3D View and press and hold
the middle mouse button (MMB) and move the mouse to rotate the view.
Blender is designed to work best with a three buttons mouse. However, if you have only a two buttons mouse
you can substitute the middle mouse button by holding ALT and the left mouse button (ALT-LMB).
Now return to the top view of the scene by pressing PAD-7. These actions should give you a basic idea of
how navigating in the 3-D space through a 2-D window works. More on this topic is covered in the Blender
15/02/2011 12:39:15
51
Pumpkin Run - Playing with 3D game technology Modeling an environment
Basics Chapter.
In the next steps we will create a ground for our game. Select the cube again by pressing RMB with your
mouse over it. The cube will be drawn in pink when your selection has been successful. Now press XKEY or
DEL to delete the cube. Blender will ask you for confirmation, if you move the mouse out of the pop-up, the
deletion will be canceled, if you agree with LMB or ENTER the cube will be deleted.
/ ■ \
I
□
3D Cursor
Newly added objects will always appear at the 3D-Cursor. The 3D-Cursor is placed by a click with the left
mouse button, LMB. Now place the 3D-Cursor in the middle of the 3D-view by clicking LMB.
Now press SPACE to call the Toolbox, this is something like the main menu of Blender. Choose
Add->Mesh->Plane and confirm the selection with LMB. A plane appears, you can check that it is really a
plane by rotating the view using the MMB and mouse movements. After that switch back to a top view using
PAD-7.
scale X: 10.0000 V: 10.0000 Z: 10.0000
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□
Scaling info in the 3D View Header
Move the mouse over the selected plane, press SKEY, and move the mouse. You can see that the plane
changes its size according to your mouse moves. Now hold CTRL while moving the mouse. The scale will
only change in steps of 0.1. Scale the plane until the size is 10.0 for all axes. To do so look at the scaling
information in the bar below the 3D View then press the left mouse button to finish the scaling operation.
If you can't reach a scale of 10.0 or want to stop the scaling action, press RMB or ESC. Furthermore, ESC will
abort every Blender procedure without making any changes to your object.
In case you can't reach a scale of 10.0, you can try to zoom out using the mouse-wheel. Furthermore it is
important where you locate the mouse cursor when calling scale with SKEY. If your mouse cursor is close to
the center of the object, you will be able to scale in big steps, if your mouse cursor is located away from your
object you scale in small amounts, but with a higher accuracy.
I will now show you how to customize the Blender screen, and especially, the window layout.
□
Move your mouse slowly over the lower edge of the 3D View until it changes to a double arrow.
Now press the MMB or RMB, a menu will appear:
15/02/2011 12:39:15 52
Pumpkin Run - Playing with 3D game technology
Modeling an environment
____
1
Join Areas
No Header
□
Click on "Split Area". Move the appearing line to the middle of the 3D View and press LMB, Blender splits
the 3D View into two identical views of the 3D scene.
Move your mouse over the right window and press SHIFT-F10. The window will change to an UV/Image
Editor this is the place in Blender to work with images and textures, which will color our real-time models.
All key presses in Blender will be executed by the active window (that is the window with the mouse over it).
There is no need to click a window to activate it.
Move your mouse back to the plane in the left 3D View and select it again in case it is not selected anymore
(i.e. not pink). Now press ALT-Z, the plane is now drawn shaded according to the light in the scene. Press
TAB and the plane will be drawn with a overlay pattern, the edges yellow and the vertices (the points that
span the face) as yellow dots. This indicates that the face is selected.
% Edit External y
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Alt!
□
Now with your mouse over the plane, press UKEY and choose "Reset" from the "UV Calculation"-menu. A
representation of the 3D coordinates of the plane will appear in the UV/Image Editor on the right, this step is
needed for mapping a 2D image (texture) onto a 3D object (in our case only a plane). This so called UV
mapping is covered in depth in further tutorials and the reference part.
Move your mouse to the right window and select Open from the Image-menu or use ALT-O.
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Relative Paths
□
Image file window
A file window opens where we can navigate on our disks and select and load images. Pressing and holding the
Menu Button on the top left with the left mouse button will give you a choice of recently-browsed paths and
15/02/2011 12:39:15
53
Pumpkin Run - Playing with 3D game technology Appending an object from an other scene
on Windows operating systems, a list of your drives.
The directory you are currently in, is shown in the top text-field. The "P" button allows you to go up one
directory (parent directory).
Using these methods, go to your disc drive and browse for the folder Tutorials /Pumpkin/textures/
and locate the concgray_q . jpg image. Click on it with the left mouse button and then choose "Open
Image", alternatively you could also click on the filename with the MMB.
□
The texture now shows up in the 3D View to the left. Now leave Edit Mode by pressing TAB.
We have just created a very simple environment, but we used many of the steps needed to create more
complex game levels, which is in fact only a good combination of the simple things we just practised!
It is now time to save your scene. To ease the process we will include the texture in the saved scene. To do so,
choose the menu "File->External Data->Pack into .blend file". A little parcel-icon will appear in the menu bar
to indicate that this scene is packed. Now use the "File->Save As" or F2 to open a file window, browse to
your hard disk (as described above), enter a name in the filename field (currently unt it led . blend) and
click the "Save File" Button in the File window.
Appending an object from an other scene
Because we can't cover modeling and the general use of Blender as a tool to create whole worlds, we load
ready-made objects. In fact, there is no special file-format in Blender to store objects, so all scenes can be
used as archives to get objects from.
□
Move your mouse over the UV/Image Editor window (the right one from the last step) and press SHIFT-F5 to
change it to a 3D View.
15/02/2011 12:39:15 54
Pumpkin Run - Playing with 3D game technology
Appending an object from an other scene
Press SHIFT-F1 with your mouse over one of the 3D Views, a File Window will appear in "Append" mode
(see Figure [append]), which allows us to load any Blender object from a scene into the current scene.
You can also use the File menu to access the Append function, but mostly a shortcut is faster.
I P d:\DolMmente\Afflsterdam\GameKiW2\Baofc\Blends\Pumpkiift
Load Library
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Pumpkln_solo.blend1
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File window in append mode
Pressing and holding the Menu Button on the top left with LMB will give you a choice of recently browsed
paths and, on Windows operating systems, a list of your drives.
The directory you are currently in is shown in the top text-field. The parent directory "P" button allows you to
go up one directory.
Using these methods, go to your DVD drive and browse for the folder Tutorials/Pumpkin/. Now click with the
left mouse button (LMB) on the filename Pumpkin_Solo .blend. The file will be opened immediately an
its contents shown in the file window.
|_sj | Pump
P |d:\Do^mBrits\Amster(Jam\fiameKilV2\Boofe\Biends\Pum»*ln5h'u!r[p|i:in_stilo,blend\Obj9cft I Load Library
Candle
Flame
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Shadow
Caneel
Load Library
Relative Paths
□
Browsing in a *. blend file
When you have entered the file, the file window will show you all the parts of the scene like in a file-browser.
Now click on "Objects" with LMB. You will see the objects contained in that scene (see Figure [browse]).
Select all objects by pressing AKEY. Confirm by pressing ENTER or clicking with LMB on the "Load
Library" button.
15/02/2011 12:39:15
55
Pumpkin Run - Playing with 3D game technology Start your (Game) Engines!
□
You can now see the pumpkin as an orange spot, sitting in the middle of the plane in the left 3D View.
Switch the right window to a second 3D view by pressing SHIFT-F5 with the mouse over the window. You
will get the same top view as in the left 3D view but drawn only shaded. Now select the camera with RMB.
Move your mouse back to the left (textured) 3D view and press CTRL-PADO. This switches the view to a
camera view.
Start your (Game) Engines!
We can now start the Blender game engine already! While pointing with the mouse over the camera view,
press PKEY and you can see the pumpkin on our textured ground. The pumpkin character has an animated
candle inside and you will see it flicker. To stop the game engine and return to Blender press ESC.
I hear you saying "That's nice, but where is the animation?" Well, give me a minute.
Move your mouse over the right 3D view and press PAD-3 to get a view from the side. Zoom into the view by
pressing PAD+ a few times or hold CTRL-MMB and move the mouse up, which will give you a smooth
zoom. You also can move the view with the MMB and mouse movements while holding SHIFT. This way we
prepare the view to move the pumpkin up.
Select the character with the RMB (click somewhere on the pumpkin), and it will outlined pink to indicate
that it is selected.
We will now enter the main command center for interactive 3D in Blender. To do so press F4 or click the
Logic Buttons icon in the icon bar.
□
The Logic Buttons
Use the menu on the left labeled "Static" to change the pumpkin to "Dynamic". This setting will enable the
character to follow the laws of physics, like falling, bouncing and reaction to collisions.
If you now start the game engine you will not see much difference, but we will change that in a minute.
15/02/2011 12:39:15 56
Pumpkin Run - Playing with 3D game technology
Realtime Materials
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□
Zoom the right 3D View out a bit (do you remember? Use CTRL-MMB or PAD+/PAD- to zoom). Make sure
that the pumpkin is still selected (pink, if not then click it with RMB), press GKEY over the right 3D View
and move the mouse. The character will follow your mouse movements in the 3D View. The GKEY starts the
so called "grab-mode" which allows you to move objects within the 3-D space.
Move the object straight up until it disappears on the top of the camera view (left 3D Window) and confirm
the new position with LMB. If you are unsure you can always cancel the operation with ESC or RMB and try
again.
Now move the mouse to the left 3D View (the camera view) and press PKEY to start the game engine. The
Pumpkin falls and rests on the ground. Press ESC to exit the game engine.
Realtime Materials
To refine the movement we need some restitute so that the pumpkin would bounce. These setting can be
found in the Materials Buttons F5. Select the ground plane and press F5 to access the Material Buttons.
Currently there is no material, so click "Add New" to add a new one. If you now start the game you will
notice that the texture is gone while the game runs. This is because Blender uses a bit more advanced material
system by default, the "Blender Multitexture Materials" (see in the Game-menu and in the reference chapter).
To solve this we could use the old "Texture Face Materials" or we can just add a texture channel to the
material. This can be done by locating the "Texture"-panel on the right of the Material Buttons and click "Add
New" there.
If the "Texture"-panel is out of reach you can pan the contents of a button window by holding MMB and
moving the mouse or using the mouse wheel. Button windows can also be zoomed with PAD- and PAD+!
15/02/2011 12:39:15
57
Pumpkin Run - Playing with 3D game technology
Interactivity
Material
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Next we will define the restiute of the ground plane. Locate the "DYN" Button in the "Material"-panel of the
Material Buttons and activate it. The buttons in the panel are changing and we can now crank up the "Restitut"
slider up to 0.8. This is a factor on how much energy the material will give back on a collision. Two objects
with both a restitute of 1.0, will bounce forever, 0.0 means no bounce back.
The pumpkin already has a material with a restitute set to 0.8, so if you now start the game engine, it will fall
and bounce like a rubber ball, just right for our fun game.
Interactivity
The Logic Buttons (F4) are logically divided into four columns. We have already used the leftmost column to
set up the object parameters to make the pumpkin fall. The three right columns are used for building the
interactivity into our game.
So lets move the pumpkin at our request.
The columns are labeled as "Sensors", "Controllers" and "Actuators". You can think of Sensors as the senses
of a life form, the Controllers are the brain and the Actuators are the muscles.
Press the "Add" button once for each row with the left mouse button to make one Logic Brick for the Sensors,
Controllers and Actuators (see Figure [p-lbs]).
□
Figure [p-lbs]. Newly-created Logic Bricks
The types of the added Logic Bricks are nearly correct, for our first task, only small changes are needed. Press
and hold the Menu Button now labeled with "Always" and choose "Keyboard" from the pop up menu.
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Pumpkin Run - Playing with 3D game technology
Interactivity
Touch
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□
Now LMB click into the "Key" field of the Keyboard Sensor. The text "Press any key" appears. Press the key
you want to use to move the player forward (I suggest UP ARROW).
Now have a closer look at the Motion Controller. We will now define how the player should move. The third
line of numbers labeled "Force" defines how much force will be applied when the Motion Controller is active.
The three numbers stand for the forces in X, Y, and Z-Axis direction.
If you look closely at the wire frame view of the player you can see that the Y-axis is pointing forward on the
player. So to move forward we need to apply a positive force along the Y-axis. To do so, click and hold on the
second number in the "Force" row with the left mouse. Drag the mouse to the right to increment the value to
about 10. You can hold the CTRL key to snap the values to decadic values. Another way to enter an exact
value is to hold SHIFT while clicking the field with the left mouse. This allows you to enter a value using the
keyboard.
Having nearly created the configuration shown in Figure [p-wire], we now need to "wire" or connect the
Logic Bricks. The wires will pass the information from Logic Brick to Logic Brick, i.e. from a Sensor to a
Controller.
□
Logic Bricks to move the player forward
Click and hold the left mouse button on the yellow ball attached to the Keyboard Sensor and drag the
appearing line to the yellow ring on the AND Controller. Release the mouse and the Logic Bricks are
connected. Now connect the yellow ball on the right side of the AND Controller with the ring on the Motion
Controller.
To delete a connection, move the mouse over the connection. The line is now drawn highlighted and can be
deleted with an XKEY or DEL key-press.
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Pumpkin Run - Playing with 3D game technology
Interactivity
Always name your Objects and Logic Bricks, this will help you to find your way through your scenes and
refer to specific Logic Bricks later. To name a Logic Brick click into the name field with LMB and enter the
name with the keyboard. However, Blender will name objects and Logic Bricks automatically with generated
unique names like "sensorl", "sensor2" or "act", "actl" etc., so you don't have to fear about name-collisions.
Now press PKEY to start the game engine and when you press the UPARROW key briefly, the player moves
passing the camera.
To make the movement more interesting, we can now add a jump. To do so enter a 20.0 in the third (z-Axis,
up) field of the Motion Controller. If you try it again in the game engine, you can see that there is a problem:
If you hold the key pressed, the pumpkin will take off into space. This is because you also apply forces when
in the air.
To solve this we have to ensure that the forces only get applied when the pumpkin touches the ground. That's
where the Touch Sensor kicks in. Add a new Sensor by clicking on "Add" in the Sensors row. Change the
type to "Touch" like you did for the Keyboard Sensor.
Wire the Touch Sensor to the AND Controller. Now the Keyboard and the Touch Sensor are connected to that
controller. The type "AND" of the controller will only trigger the Motion Actuator when the key is pressed
AND the player touches the ground. This is an easy way to add logic to your interactive scenes. As well as the
AND Controller there are also OR, Expression and Python (Blender's scripting language) Controllers which
all offers more flexibility to make your game-logic. Because the forces are now applied only a fraction of a
second we might adjust them to higher values, 50.0 for force Y and 100.0 for force along the Z-axis should
get you started, feel free to experiment here to get a idea how the forces work.
At this moment, space in the Logic Buttons can get sparse. But beside changing the window layout we also
can collapse the Logic Bricks. To do so, press the little orange arrow right beneath the brick's name (so that
you are still able to see the connections, though the content is hidden).
To make the movement more dynamic, we will now add Logic Bricks to make the pumpkin jump constantly.
Add a new Controller and a new Actuator by clicking "Add" in the appropriate row. Name the new Actuator
"AlwaysJump". Wire the Touch Sensor with the new AND Controller input and the output of the Controller to
the new Motion Actuator "Always Jump".
( Touch
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□
Logic Bricks for adding a constant jump
Yes, not only one Controller can be connected to two Sensors, a sensor can also "feed" two or more
controllers. Start the game again with PKEY, the pumpkin jumps, UPARROW moves it forward
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Pumpkin Run - Playing with 3D game technology
More control
More control
Now we add more Logic Bricks to steer the player with the cursor keys.
Add a new Sensor, Controller and an Actuator by clicking on the "Add" Buttons. Change the Sensor type to
"Keyboard" with the Menu Button and assign the left cursor key to the Sensor. Don't forget to name the Logic
Bricks by clicking on the name field in the bricks. Wire the Sensor ("LeftArrow") with the Controller
("pass2") and the Controller output with the Actuator ("Left")
□
Logic Bricks to steer the player
Enter "3.0" in the third field (Z-axis) in the "Torque" row. Torque is the force that turns the object. In this case
it will turn the actor around its longitudinal axis. Try it in the game engine, the pumpkin will turn left when
you press LEFTARROW. Repeat the steps but change it to turn right. To do so use RIGHT ARROW and enter
a torque of "-3.0". See Figure x-y.
It is most likely that we nee to adjust or fine tune the controls later in the game, this is a iterative process
which need some experience.
Camera control
In this section, I will show you how to set up a camera which follows the actor, trying to mimic a real
cameraman.
Move your mouse over the right 3D view (the wire frame or shaded view) and zoom out with PAD- or
CTRL-MMB movements. Locate the camera and select it with RMB.
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Pumpkin Run - Playing with 3D game technology
Camera control
□
Ensure that the Logic Buttons (F4) are still open. Now add a Sensor, Controller and an Actuator as you
learned above. Wire the Logic Bricks and Change the Actuator into a Camera Actuator. The Camera Actuator
will follow the Object in a flexible way which gives smooth motions.
□
Logic Bricks
Click the "OB:" field in the Camera Actuator and enter the name of the pumpkin object, here "Pump". The
camera will follow this object. Click and hold the "Height:" field with the LMB and move the mouse to the
right to increase the value to about 2.0. This is the height the camera will stay at.
Holding CTRL while adjusting a Number Button will change the value in stages making it easier to adjust the
value. SHIFT-LMB on a Number Button lets you use the keyboard to enter values.
The Min: and Max: fields determine the minimal and maximum distance the camera will get to the object. I
chose "Min: 4.0" and "Max: 7.0". Start the game engine to test the Camera Actuator. Experiment a bit with the
values.
Real-time Light
Real-time lighting in Blenders game engine is performed by the OpenGL subsystem and takes advantage of
hardware accelerated transform and lighting if your graphics card provides it.
□
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62
Pumpkin Run - Playing with 3D game technology Real-time Light
Difference between a lit and unlit pumpkin
Locate the lamp in a 3D View and select it with RMB. Use GKEY to move it and watch the effect on the
textured view on the pumpkin. For reference, the left pumpkin in Figure [p-lig] is lit, the right one is not. Try
to move the light around in the 3D Views so you can see that the textured view gets updated in real-time.
Moving the light under the pumpkin gives a scary look, for example.
The real-time lighting in Blender doesn't cast shadows. The shadow of the pumpkin is created differently.
Also, bear in mind, that real-time lights cause a slowdown in your games. So try to keep the number of objects
with real-time light as low as possible.
More options for lamps and real-time lighting are covered in the Reference section.
Object Animation
Here I will cover the basics of combining Blenders animation system with the game engine. The animation
curves (Ipos) in Blender are fully integrated and give you full control of animations both in conventional
(linear) animation and in the interactive 3D graphics covered by this book.
Use SHIFT-F1 or use the File-menu "Append or Link". Browse to the books disk, choose
Tutorials/Pumpkin/Door . blend, click on Object, select all objects with AKEY, confirm with
ENTER. This will append a wall with a wooden door to the scene. The pumpkin will bump against the walls
and the door. The collision detection is handled by the Blender game engine automatically.
Switch the right 3D View to a Top View (PAD7) and zoom (PAD+ or PAD-) as needed to see the appended
door completely. The door has the name and the axis enabled, so it should be easy visible, for easier access
switch the view to a wire frame view (ZKEY). Select the door with RMB (it will turn pink).
We will now make a simple key frame animation:
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□
1. Ensure that the Frame Slider (the current animation frame) is at frame 1 by pressing
SHIFT-LEFT ARROW
2. IKEY, select "Rot" from the menu
3. Now advance the animation time by pressing CURSORUP five times to frame 61. With the game
engine playing 60 frames per second our animation will play now 2 seconds.
4. Press RKEY (be sure to have your mouse over the top view) and rotate the door 150A° clockwise.
You can see the degree of rotation in the Header of the 3D View. To make it easier to rotate exactly,
hold CTRL while rotating.
5. Now insert a second key by pressing IKEY and again choosing "Rot"
6. Move to frame 1 by pressing SHIFT-LEFT ARROW and press SHIFT-ALT-A, you will see the
animation of the door being played back. After 51 frames the animation will continue to frame 250
and then repeat.
7. Press ESC to stop the playing animation.
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Pumpkin Run - Playing with 3D game technology
Object Animation
Insert Key
Loc
Scale
LocRot
LocScale
LocRotScale
RotScale
VisualLoc
VisualRot
VisualLocRot
Layer
Available
Mesh
With the door still selected switch the Buttons Window to the Logic Buttons, by pressing F4. Add a Sensor,
Controller and Actuator, wire them, name them, change the Sensor to a Keyboard Sensor and change the
Actuator to "Ipo" type.
Change the type of the Ipo Actuator to "Ping Pong" mode using the Menu Button. SHIFT-LMB "End" and
change the value into "61" (see Figure [p-ipo]). This way the Ipo Actuator plays the door animation from
frame 1 to 61 which opens the door. A new invocation of the Ipo Actuator will then close the door (because of
playing it "Ping Pong").
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□
Logic Bricks for playing an Ipo in "Ping Pong" mode
Play the scene (PKEY) in the textured view, and the door will now open and close when you press SPACE
and can push the actor around if he gets hit by the door. To visualize the animation curves (Ipos) switch one
window to an Ipo Window by pressing SHIFT-F6.
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Pumpkin Run - Playing with 3D game technology
Refining the scene
Refining the scene
You may have noticed there is currently a problem in the file: The actor can "climb" (nearly takes off like a
rocket) the wall because we can jump on every touch of any object even on a wall.
Select the pumpkin and look at the Touch Sensor, the "MA:" field is empty. "MA:" stands for a material
name. If you fill in a material name here, the Touch Sensor will only react to objects with this material. In our
scene this would be the ground we created at the beginning.
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□
So now select the ground plane and switch to the Material Buttons F5. Locate the "Links and Pipeline"-panel
and change the name of the material by clicking it with the left mouse button and entering "Ground".
Now, select the pumpkin again, switch back to the Logic Buttons F4 and enter "Ground" into the "MA:" field
of the Touch Sensor.
Whether a name is capitalized or not makes a difference in Blender. So a Material called "ground" is not the
same as "Ground". Blender will blank a button when you enter an object name which does not exist. This may
sound frustrating but it really helps while debugging, because it prevents you from overlooking a simple typo.
Try again to hop around, now you now cannot climb the wall anymore.
□
At this point you may want to place the camera more behind the pumpkin, so that the view during the game is
better and also move the light in a way that the pumpkin gets lit better. It is best to do such things in the top
view, using GKEY to move and RKEY to rotate and controlling the effect in the camera view.
One last thing: it would be nice if the door would only open when the actor is close to it. The Near Sensor will
help us here.
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Pumpkin Run - Playing with 3D game technology
Adding Sound to our scene
Add a new Sensor to the door and change the Sensor type to "Near". Wire it to the existing AND Controller
(see Figure [p-near]). The "Dist:" field gives the distance at which the Near Sensor starts to react to the actor.
By the way, it will react to every actor if we leave the "Property:" field empty. The "Reset: 12.0" field is the
distance between the Near Sensor and the object where the Near Sensor "forgets" the actor. Try to make the
"Dist:" setting to 4.0, now you need to come close to the door first but then you can back up before you press
SPACE to open the door without the danger of getting hit. Now the door only opens when you press SPACE
and the pumpkin is near the door, good for levels with more than one door.
Add
Keyboard SpaceKey
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□
Near Sensor
Adding Sound to our scene
There is no game without sound, so I will show here how to add a sound to an event in Blender.
a m ^ v
□
Locate the Sound Buttons icon in the icons of the Display Buttons F10. Click the icon with the left mouse
button to switch to the Sound Buttons. Because there is no sound in the scene the "Sound"-panel will be near
empty. Use the Menu Button under "Blender Sound block" (click and hold) to choose "OPEN NEW". A file
window opens, browse to get to the CD-ROM and load DoorOpen.wav from the directory
Tutorials /Pumpkin /samples/.
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Blender Sound bloci;
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volume: i .ooaH
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3D Sound
Velscily: 340 .29
□
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Pumpkin Run - Playing with 3D game technology
Last words
The Sound Buttons with a sound loaded
Blender is capable of creating 3D sound (Sound located spatial in the scene) and provides many ways to
influence the sound. But for the moment we can go with the defaults and don't need to touch any of these
buttons. Of course you can play the sound by clicking on the big "Play" button.
Select the door object (RMB) and switch to the Logic Buttons with F4. Add a new Actuator and change the
type to "Sound". Wire it to the Controller (see Figure x-yA). Click and hold the solitary Menu Button in the
Sound Actuator and choose the sound file "DoorOpen.wav" from the pop-up menu. As a last step before you
can try it, change the mode "Play Stop" to "Play End" this means the whole sound is played without stopping
too early.
□
In the same manner you can load the sound "bounce.wav" and add this sound to the pumpkin. Just make sure
that you connect the Sound Actuator with the right Controller, the one which is also connected to the "Always
Jump" Actuator. This way every time the pumpkin touches the ground, a bumpy sound will be played.
Last words
After this chapter you should have an idea what it is about to make a game with Blender. We did some of the
basic steps and you are now prepared to do other tutorials or start playing with ready made scenes or your own
ideas. I would encourage you to experiment a bit more with the pumpkin scene, also check out the additional
scenes in the pumpkin folder on the disk.
I suggest that you continue with the chapter "The Blender Basics", and read it at least one time so that you
know where to look when you face problems. Also don't hesitate to use our support, see the Appendix for
links to the forums and online resources.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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67
Tube Cleaner
Tube Cleaner, a simple shooting game
Figure x-y. Tube Cleaner game
Tube Cleaner was designed by Freid Lachnowicz. The game is a simple shooter game that takes place in a
tube. Three kinds of enemies are present. Try to collect as many points and bullets as you can on your way up
the tube!
To play the game in its final stage load the scene Games/TubeCleaner . blend from the DVD. It
includes instructions.
This Tutorial is not supposed to explain how to make the full game. But you should be able to understand the
extensions in the final result (you can also look for cheat codes in the game...) with the help of this book and
this tutorial. And of course you are encouraged to change and extend the game to your liking!
Tube Cleaner game controls
Controls
Description
CURSOR KEYS
rotate the cannon left, right, up and down
SPACE
Shoot
Loading the models
Start Blender and load Tutorials /TubeCleaner/TubeCleaner_0 .blend from the disk. This
scene contains all models to start. To make the scene interactive, this tutorial will lead you through the
following tasks:
1. Adding game logic to the gun, allowing it to move up, turn and shoot
2. Adding game logic to the enemies
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68
Tube Cleaner
3. Creating the score system including display
Loading the models
□
Figure a-b. Wireframe top view in the loaded Tube Cleaner scene
The scene contains a camera view on the left, a wireframe view (view from top) on the right and a the Logic
Buttons on the bottom. In the top view (Figure a-b) you can see the "Base" object is already selected and
active (purple color in wireframe). The "Base"-object will carry the cannon and will contain some of the
global logic of the game. The cannon itself is parented to this "Base". This hierarchy will make our job later
easier because we won't have to worry about composite movements.
Controls for the base and cannon
We start with the rotation around the vertical axis of the base. This will also rotate the cannon and the camera
because they are parented to the base.
Make sure that the "Base" object is selected (pink, RMB to select if not) and click on the "Add" Buttons in the
Logic Buttons F4 for each row of Sensors, Controllers and Actuators. In every row a new Logic Brick will
appear.
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□
Figure [TC-1]. Logic Bricks to rotate the gun
15/02/2011 12:39:15
69
Tube Cleaner Controls for the base and cannon
Now link (wire) the Logic Bricks by clicking and drawing a line from the little yellow balls (outputs) to the
yellow donuts (input) of the Logic Bricks. These connections will pass the information between the Logic
Bricks. Change the first Logic Brick to a Keyboard Sensor by click and hold its Menu Button with the left
mouse button and select "Keyboard" from the pop up menu.
Please (re)do the tutorial in the "Pumpkin Run" chapter if you have problems with the creating, changing and
linking of Logic Bricks.
Now, click the "Key" field with the LMB and press the RIGHT ARROW key when prompted by "Press any
key" in the Keyboard Sensor. The "Key" field now displays "Rightarrow" and the Keyboard Sensor now
reacts to this key only.
Now change the third number (Z-Axis) in the "dRot" row of the Motion Actuator to -0.03. Do this by using
SHIFT-LMB on the number and entering the value with the keyboard. The three fields always denote the
three axis (X,Y,Z) of an object. So we will rotate around the Z-axis.
Now move your mouse cursor over the camera view and press PKEY to start the game. You should now be
able to rotate the gun with the right cursor key.
You should always name your Logic Bricks and other newly created elements in your scenes (click on the
default name and edit with your keyboard). This will help you to find and understand the logic later. Take
Figure [TC-1] as a reference.
Use the same procedure as above to add Logic Bricks to rotate the gun to the left. Use LEFT ARROW as key
in the Keyboard Sensor and enter "0.03" in the third "dLoc" field of the Motion Actuator.
As you can see the space in the Logic Buttons is getting sparse with only six Logic Bricks. Use the little
orange arrow icon in the Logic Bricks to collapse the Logic Bricks to just showing a title. Now you also see
another good reason for properly naming Logic Bricks.
Upwards Movement
In "Tube Cleaner" we want to have a continuous upwards movement within the tube. We could achieve this
similarly to the rotation of the gun, but there is another way which will give us much more control over the
movement and also allows you to move down to a specific level of the tube.
The method used here is to combine the possibilities of Blender's game engine and its powerful animation
system. Move your mouse cursor over the camera view and press ALT-A, Blender will play back the
animations already defined in the scene. Press ESC to stop the playback. But so far none of these animations
is played back by the game engine. We have to tell the objects to play the animation. This way we can
interactively control animations, for example play, stop or suspend.
15/02/2011 12:39:15 70
Tube Cleaner
Upwards Movement
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□
Figure [tc-ipo]. Ipo Window with the animation curve for upward movement
Move your mouse cursor over the wireframe view and press SHIFT-F6. The window will change to an Ipo
Window (see Figure [tc-ipo]), meant for displaying and editing Blender's animation curves. The Ipo Window
is organized into axes, here the axes are the horizontal axis, showing the time in Blender's animation frames
and the vertical axis showing Blender units. The yellow vertical line is the animation curve for the movement
along the Z-Axis of the "Base" object, meaning upward movement for our object. So to move the object 10
units up you can move the Ipo cursor (green line) with a left mouse click to frame 10. The camera view will
reflect this immediately.
To play this animation in the game engine, we use a special Logic Brick the "Ipo Actuator", set to "Property"
play type. A Property is a variable owned by a game object, which can store values or strings. We will now
create a new property which will hold the height (zLoc(ation)) of the "Base" object. To do so click on "ADD
property" in the Logic Buttons for the "Base" object.
Click on "Name:" and change the default name "prop" to "zLoc", this Property will hold the height of the gun
in the tube.
Blender uses capitalization to distinguish between names of Objects and Properties. So "zloc" is not the same
as "zLoc".
Continue creating the Logic Bricks from Figure [tc-lbup]. The Always Sensor triggers the logic for every
frame of the game engine animation, ensuring constant movement. The AND Controller just passes the pulses
to two Actuators, both are connected to the Controller and will be activated at the same frame.
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Figure [tc-lbup]. Logic Bricks for the upward movement
The Ipo Actuator will play the Ipo animation according to the value in the Property "zLoc". To get a constant
motion we increase the "zLoc" Property every frame with the Property Actuator . In this case it is of the type
"Add" which adds "Value:" (here 0.01) to the "zLoc" Property every frame. Try to change the "Value:" to get
a feeling for the speed of the animation. If you'd like to move the cannon downwards try entering -0.01 into
the "Value:" field. After experimenting a bit please use 0.01 for the value field as shown in Figure [tc-lbup].
To play the game at this stage move your mouse to the camera view and press PKEY.
15/02/2011 12:39:15
71
Tube Cleaner
Shooting
Blender can show you the used Properties and their values while the game runs. To do so, choose "Show
debug properties" from the "Game" menu and activate the "D" Buttons (Debug) for every Property you'd like
to have printed on screen
Shooting
□
Switch the Ipo Window back to a 3D View by pressing SHIFT-F5 over the Ipo Window. Now select the
"Gun" object with the right mouse. You can click on every wire from the "Gun" object, a proper selection will
be reflected in the lower left corner of the 3D View and in the Logic Buttons where "Gun" will appear in the
columns for the Logic Bricks.
Now add a Sensor, Controller and Actuator to the "Gun" object and wire them as you learned earlier in the
tutorials. Change the Sensor to a Keyboard Sensor (please name the Sensor "Space") and choose (click in the
"Key" field) Space as trigger for the gun. Change the Actuator to an "Edit Object" Actuator. The default type
is "Add Object" which adds an object dynamically when the Actuator is triggered.
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□
Figure tc-fire. Logic Bricks to fire the gun
Enter "bullet" into the "OB:" field by clicking it with LMB and using the keyboard to enter the name. This
will add the object "bullet", a pre-made object, which is on a hidden layer in the scene. Enter 18.00 as the
second number in the "linV" fields. This will give the bullet an initial speed. Also activate (press) the little "L"
button behind the "linV" row. This way the bullets will always leave the gun in the direction aimed. Enter 50
in the "Time:" field this will limit the life time of the bullets to 50 frames, avoiding ricochets to bounce
forever. As usual, now try to run the game now and shoot a bit.
So far we have unlimited ammunition. To change this we again use a Property storing the number of bullets
left. Add a new Property by clicking on "ADD property". Name this Property "bullets" and change its type to
"Int" with the Menu Button now labeled "Float" (the standard type for new Properties). An "Int(eger)"
Property only holds whole numbers, this is ideal for our bullets as we don't want half bullets. SHIFT-LMB on
the field to the right of the "Name:" field to enter 10 here. This is the initial number of bullets available at the
start of the game.
1
Add
All Inl D
XJEdttOBjacl ~ || AfldBullal
Add Qb|ed
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□
To actually decrease the number of bullets on every shot we use the "Property Add" Actuator that we also
used to make the base of the cannon move up. So add another Actuator by clicking on "Add" in the Actuator's
column of the gun. Wire it to the AND Controller we created in the last step. Change the Actuator type to
"Property" choose "Add" as the action. Enter "bullets" in the "Prop:" field and -1 in the "Value:" field. This
will subtract 1 (or add -1) from the Property "bullets" on every shot triggered by Space.
□
So far the gun doesn't take any notice of the number of bullets. To change this we will use an Expression
Controller which allows to add single line expressions to process game logic. Change the AND Controller
with the Menu Button to an Expression Controller. Then click then on the "Exp:" field and enter "Space AND
bullets>0" (without the quotation marks) and press ENTER. Here "Space" is the name (exactly as you typed it
in the Logic Brick) of the Keyboard Sensor and "bullets" is the bullets Property. The Controller now only
activates the following Actuators if the Sensor "Space" is active (meaning that Space is pressed) AND bullets
is bigger than zero. Try again to run the game, you now can only shoot 10 times. Read more about
Expressions in Section [Expressions] .
The last step to make the gun work is to make the bullets display functional. Select the display (the right one
with the flash on it) with the right mouse button. It is best to hit the little dot on the " @ " sign (which is a
visual hint for placing the object). The name "BulletsDisplay" should appear in the Logic Buttons and in the
3D View. Alternatively you can zoom into the wireframe view to make the selection easier.
You can see in the Logic Buttons that there is already a Property called "Text" for the display object. The
object has a special text-texture assigned which will display any information in the Property called "Text" that
is on it. You can test this by changing the value "10" in the Property, the change will be displayed
immediately (a bit covered by the " @ " sign) in the camera view and also during runtime of the game.
Because Properties are local to the object they are owned by, we have to find a way to pass the values of
Properties between objects. Inside a single scene this can be done with the Property Copy Actuator. Another
way would be to use messages, in this case you can also pass information between multiple scenes.
Add a line of Logic Bricks to the "BulletsDisplay" like you did before and wire them. Change the Actuator to
a Property Actuator, type "Copy". See Figure [tc-copy].
RIM' 1 'i^i.jjsi
n ■ ! 1 It 1 II 1 1! , I , , 1 -; M l ll "l«l
□
Figure [tc-copy] . Logic Bricks to display the amount of bullets
Enter "Text" into the first "Prop:" field, this is the name of the Property we copy into. Enter "Gun" into the
"OB:" field, again watch for correct capitalization, Blender will blank the input field if you enter a
non-existing object. From this object we will get the value. Enter "bullets" into the field "Prop:" beneath
"OB:" this is the Property name from which we get the value. It is not needed to actually copy the information
in every frame, so enter a 10 in the "f:" field of the Always Sensor, this will copy the Property every 10th
frame (about 1/6 of a second) and will so preserve performance.
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Start the game and shoot until you have no more bullets.
More control for the gun
More control for the gun
Tilting the gun will add more freedom in movement and dynamic to the game. We will use a similar
technique as for the movement up, by combining animation curves and Logic Bricks.
Select the gun and collapse the Logic Bricks by clicking their arrow icons D, this will give us more space for
the coming logic.
As for the upward movement of the gun, it already contains a motion curve that we can use. We also need a
Property which contains the actual rotation (tilt, rotation around x-axis). So add a new Property by clicking on
"ADD property" and name it "rotgun".
Again use the "Add" Buttons to add a Sensor, Controller and one... nope, you are right this time two
Actuators. You already know this from the upward movement. We need one Actuator to change the Property
and one to play the Ipo. Wire the new Logic Bricks, as shown in Figure [tc-up]. The collapsed Logic Bricks
are the ones you made for shooting.
X i« Obiscl JiMBuiiel
> Property tolgtm*!
F„ P
rtfgim
|V*lu* I "
U|W
lpc Gin
I , ( -,*
I] F«t 1
AIM |
Pic? imguri
L'll'J
□
Figure [tc-up]. Logic Bricks to rotate the gun upwards
Change the Bricks according to Figure [tc-up] and enter all the necessary information. Using the Property Add
Actuator we increase "rotgun" by one every time UP ARROW is pressed and then play the Ipo according to
the "rotgun" Property, this will rotate the gun up.
Now test the game. Every time you press UP ARROW the gun will rotate a bit up. Stop the game with ESC.
To get a continuous motion we have to activate the pulse mode icon for the Keyboard Sensor, this will give a
keyboard repeat here, so the gun will rotate as long as you press the key without the need to release it.
Now test the rotation again, and you will see that the gun only rotates a specific amount and then stops. This is
because of the animation curve (Ipo), you can visualize the curve when you switch a window to an Ipo
Window using SHIFT-F6 (use SHIFT-F5 to return to the 3D View). You can see that the curves are
horizontally from frame 21 (horizontal axis), meaning no further rotation is possible. You also see that we
need to make the "rotgun" negative to rotate down.
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More control for the gun
-41} -30 -20 -10 10 20 30 40 ■
' View Select Marker Curve 1%' |*|^ Object |/| -|lP:IPOgUN |x | F j p*4+| [£] J
□
Again add a Sensor, Controller and one (yes, this time, it's really only one) Actuator. Wire and name them as
shown in Figure [tc-rot]. Note that we use the Ipo Actuator for the tilting down also. This is perfectly ok, we
can save this way a Logic Brick. It would have also been working ok to use a second Ipo Actuator here.
_XJ KGylMaia Sfntti
Keyboart : upa-'row
■to >| l*Kl | Hrv
trpura* I MCWyl
IN;
H E-pretilon r o:ti
1 □>
X *n:i ccnii
jcJrapMy nwisK-i
ifflgun ,1
Add
F-: ' :: : v ,.;:
!P0 ?U"
"•■:■!!•.
Pidp iM&jun
Pin, 1; i.-' : ,™ I
Pofd Md
2
a
"O
PiCj. folguf--
V*)UB; -1
□
Figure [tc-rot]. Completed Logic Bricks to tilt the gun
If you prefer "pilot-controls" just swap the UpArrow and DownArrow in the Keyboard Sensors.
There is one drawback: if you press UP for too long the gun will stop rotating but "rotgun" is still
incremented. This will cause that the cannon is not rotating back immediately when you press DOWN again.
To prevent this we can use an Expression Controller again, see Figure [tc-exp] for the correct Expressions.
TJj) X I Expression cont
X | Expressio i j jcorrtl
_^j ExpUparrow AND rotc(un<21
X | Expressio - cortt2
r
|EKp:Downarrow ftND iotgun>-2i
□
Figure [tc-exp] . Expressions to correctly stop the rotation
These Expressions will prevent "rotgun" from counting when "rotgun" is already greater than 21 or less than
-21.
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Tube Cleaner An enemy to shoot at
It is time to save your project now ! Blender scenes are usually very compact so saving only takes seconds.
First you need to pack (include in the Blenderfile) the textures, use the "File-menu->External Data->Pack into
.blend file" to do so. Then save the file to your hard disk. This makes sure that all textures (and in case also
sounds and fonts) will be on your harddisk, so that opening the file again will not need the books disk
inserted.
This way you can also send the file to a friend by e-mail and he will get all textures with the game.
For further working on the scene it is recommended to unpack the data again with "File-menu->Externak
Data->Unpack into Files...", then choosing "Use files in current directory (create when necessary)".
An enemy to shoot at
□
It is now time to add something to shoot at. Select the "Target" object with the right mouse, it may be needed
to rotate the view a bit using MMB and mouse movements to get a good view.
The tasks a game logic on the enemy has to do are:
1 . React on to hits (collisions) with the bullets
2. Make a silly face when hit, and die
3. Add some points to the players score
You can see that I try to keep the game logic on the target itself. Although it is possible to put all that to the
player or any other central element, it would make a very complex and difficult to maintain logic for this
object. Another advantage of using local game logic is that it makes it much easier to re-use the objects and
the logic, even in other scenes.
We start again by adding a Sensor, Controller and an Actuator and wiring them. You should be familiar with
that procedure by now. To react to a collision, change the Sensor to a Collision Sensor. Enter "bullet" into the
"Property:" field, this is the name of a Property carried by the bullet, this way the Collision Sensor will only
react to collisions with bullets.
Change the Actuator to an Edit Object Actuator and choose "Replace Mesh" as the type. Enter "TargetDead"
into the "ME:" field. This mesh show the dead target and will be shown from now on when you hit the target
with a bullet. The dead target is on a hidden Layer, you can look at it when you switch Layer 11 on by
pressing SHIFT- ALT- 1 KEY.
« S3 Bkm3
xIaho
X
L.J.IOL,.
RSplit*TlrjilM«i I
"■?pi*<* '■■■■-■ r
1
'.'- I :,,a.:;,a
□
Figure x-y. Logic Bricks to make the target look silly
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Tube Cleaner
An enemy to shoot at
Don't forget to switch of Layer 1 1 again with SHIFT-ALT-1KEY, or shooting will not function properly. This
is because all added objects need to be in a hidden layer to make the Add Object Actuator work.
^&
x Ettii Object * [r RsplaceTaraelMesti
Rsplace Mesh
METargelDaad
X Message Send 10 Points
Fsr
Subject 1 points
T/P
Body:
□
To actually score a hit we will use Blender's messaging system. This allows us to send messages from objects
to objects. In this case we will signal the score-display to add some points to our score. So add a second
Actuator to the target, wire it with the existing Controller and change it to a Message Actuator.
We can leave the "To:" and "Body:" fields blank, just fill in the "Subject:" field with "lOpoints". This is equal
to shouting into the room and the score-keeper will note the score.
□
We now need to set up the score display to react to the score messages. Select the "Score-display" object and
add Logic Bricks as shown in Figure [tc-score].
□
Figure [tc-score]. Logic Bricks to count the score
The "Score-display" is again an object with a special texture on it showing the content of the "Text" property
as explained for the bullets display. Be sure to change the 999 to zero or the score will start with 999 points.
The Message Sensor will only hear messages with the "lOpoints" subject and then trigger the Property
Actuator to add 10 to the "Text" Property which is then displayed. This way it is also very easy to add
different scores to different actions, just add a new line of Logic Bricks listening for different subjects and
then add the appropriate amount of points.
You should now try out the game so far and shoot at the enemy. This should add 10 points to your score. If
anything fails to work, check especially the correct wiring, and that the names and capitalization of Properties
and message subjects are as they should be.
In the final game the targets start to slide down the tube, look at Figure [tc-adv] for a possible solution for
that. The simple target also has the drawback that it will still add a score when you hit a dead target.
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Tube Cleaner
An enemy to shoot at
XleanOttrd Fnppsjf(r*.gaiMiisii jj|
Ml Mets-SgS Send 10 FaMt
Probity
□
Figure [tc-adv] . Advanced animation for dead targets
We have already used most of these Logic Bricks. Basically it just uses an Expression Controller to avoid
counting scores by shooting on dead targets. This is done by checking the frame Property for being zero
which gets increased by one when a hit occurs. As soon as frame is one a Property Sensor type "Interval" fires
as long as frame is between 1 and 200, this triggers adding frame by one and sliding the target a bit down in
every frame. When frame reaches 200 the object gets killed by the Edit Object Actuator.
Now you can place more targets in the tube. For that select the target, then use ALT-D to copy it. Now use
grabbing (GEKEY) and rotating (RKEY, use CTRL for a snap) to place the new enemy.
Together with the reference part of this book and the final game on the disk you can now try to extend the file
or just enjoy playing the game. Don't desperate and keep on experimenting. By breaking the task into small
steps, even complex logic is possible without getting lost.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Pinball
A pinball game is a nice thing to test a physics engine. The fast motions will stress the collision system to the
max.
□
As theme I choose a construction site, I did not try to mimic a real pinball that much but looked for some
special effects like the accident mode in the tunnels, the sewer mode or the brickmode which would be not
possible in a real arcade flipper. Load the file Tutorials /Pinball /Pinball .blend and press PKEY
to play.
Function
Key
Add Ball
BKEY
Flipper left
CKEY
Flipper right
MKEY
Shoot Ball
RETURN
Use of the elements
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Pinball
Use of the elements
□
All elements like the bumpers, flippers etc. in the game are groups in hidden layers (see layers 11-20) for easy
re-use. This also allows to quickly change already placed elements without a hassle.
□
For easy constructing the game and placing the elements, I parented all elements to a master empty, then
before playing I rotate the master empty so that the desired slant is achived.
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Pinball
Bumpers
IpKu *•
Math >
Edit ►
Curve ►
Select ►
Surface ►
TrarlifOrm *
Mela *
Object ►
Text
Visw r>
Empty
Fender *
Mkffiffil ►
Accident
Camera
Sail
Lamp ►
Armature
Lattice
Barrier
0all_bad
BrickAdd
C or crete Block
FlipperR
Leitfcegel
RC Ji: Di£ i.H
HoadMoolcW
Srtorjlef
Sign
WamLight
□
So the usual way to edit look like this:
1. switch to frame 2, the pinball table is now leveled
2. add element or group
3. parent the element or group (STRG-P) to the master empty
4. if wanted copy now the element or group with ALT-D, all copies are automatically parented also to
the master empty
5. switch to frame 1
6. play the game
Other ideas for elements could be:
• construction site sounds
• pipes (working as ball ramps)
• sand "hills" or sand ground (slows the ball)
• caterpillar (moving, can manipulate the ball or "protect" an extra)
• scaffolds
• ramps made of shelves
• containers
Bumpers
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Pinball
The Sewer
1 I BV I J^ (J
□
All bumpers follow the same principle, the objects itself have no collision set, instead a invisible simple object
surrounds them. This surrounding object plays an Ipo upon contact to give the ball an extra hit on contact.
nwpgna w feres | MB
an t=-in ^ cr m
-'..:■■ -'Pirn
Play EM
Ka
■ wiro-hOM »' Pltm: 0X0,
-' Mesiaga Score
r^r
|Subfecb seara
□
The Logic Bricks are only a Collision Sensor which triggers the Ipo, plays a sound and sends a score message.
The Sewer
□
The sewer effect is played when the ball falls into the hole on the street. Here we just have an object which
kills the ball (all objects having a Property "kill" will kill the ball, the logic is on the ball itself) and sends a
message to the sewer.
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Pinball
The Sewer
The sewer is assembled out of four parts, the manhole cover, an Empty which will add a new ball with the
Add Object Actuator and a water fountain which is deformed by an Armature.
□
The logic of the sewer contains four new logic elements which were developed by Benoit Bolsee for the
Apricot Project and are now part of Blender 2.48: The NAND Controller, the Delay Sensor, the State system
and the Actuator Sensor.
Let's start with the easy pail, how the ball is added:
AddBallFountain This is just an Empty, it has an Ipo which is always played in Ping Pong mode and so that
the new added ball will start with a new direction (pseudo randomly) every time. At a specific time
(depending on the whole animation) the ball is added by triggering a Add Object Actuator.
Now the complicated part, syncing the Actions and Ipos of the fountain:
Sewer This object is the manhole cover and contains the most complicated logic. It has two states, the initial
one which just sits there and waits for a message with the subject "Fountain" and triggers the second state
when it arrives. The second state plays an Ipo animation of the manhole cover and a action on a Armature
which deforms the water fountain.
The Delay Sensor waits some seconds then it triggers the water sound, the Ipo animation of the
manhole cover and the Action for the Armature
The Actuator Sensor is triggered as long as the sewer Ipo Actuator is played. When the Ipo is over,
it will trigger the State Actuator to go to state 1 again. This is achived with the use of a NAND
Controller.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Subracer
The "Subracer" game features some recent developments which were made for the Apricot Project. This
includes GLSL Materials (nomal maps, caustic maps, reflection maps), GLSL mist (nicer and more flexible
than the normal BGE mist) and GLSL Shadows.
The game idea, concept, game logic, physics, scripts, the ship, the HUD and the cockpit, the gates, mines and
special effects were made by me, Carsten Wartmann.
The level (the rocks, sandy ground, plants, ancient columns) and the ship design was made by Christopher
Plush (blengine), thank you Chris!
Originally it was planned as a (nowadays) submarine game, where you supposed to perform missions under
water, however, it turned more and more into a SF-racing-arcade game and as the ship design was looking
more than a aircraft I switched the idea to the current one. For the short amount of time I am pleased whith the
game play, at least there is a goal in having a good round time. Beside of that the game demonstrates many
things common for games, like the working HUD (Head Up Display), multiple camera perspectives, scripts
for timing and organizing.
So now load the game from the books disk (B lends / Subr ace r / Sub r a cer_pa eked, blend) and drive
a bit around. You need to go through the gates in the specified sequence to complete a round. The indicator in
the middle of the HUD will tell you which gate next, the rough direction of the next gate and if you are on a
course towards the gate (green gate indicator) or away from the gate (red indicator). Collect the crates, they
will give you 100 units turbo fuel. After completing a round your time will be displayed in the "R-TIME"
field. Note that with no thrust the ship is hard to control, so use small thrust strokes to keep your ship on
course in slow passages.
Subracer game controls
Controls
Description
CURSOR KEYS
Turning left/right and pitch up/down (pilot controls)!
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Subracer
Ship setup
WKEY
Forward thrust
QKEY
Turbo speedup (as long there is enough turbo fuel, see HUD)
AKEY/DKEY
Roll the ship, this is not needed always but can save you in some situations
SPACE
Fire the sonic gun to blast mines
RKEY
Restart the game
Fl
First person perspective
F2
Third person perspective
This game is based on advanced GLSL materials and lights. So if your graphic card does not support this you
can switch of GLSL (Texture Face Materials) or parts of (GLSL Material Settings) it in the "Game"-menu.
However, the game will then not look very good anymore.
Ship setup
The ship consists of several objects, see figure [racer- 1] for an overview.
□
Figure [racer- 1]. Ship setup
The main ship object is only a invisible cage surrounding roughly the ship mesh you will see in the game.
This is to lower amount of collision detection for the physics engine, we use a "Triangle Mesh" bounds type
(see figure [racer-2]), so we can get stuck with the tanks on the wings for example at other objects. The ship
you see in the game has a much higher resolution but all faces are set to no collision.
You can also see the two Cameras and two spotlights, one from above for generating the shadow of the ship
on the ground and one which is the search headlight. The shadow from the ship is important to give the eye a
hint how near the ground is, of course it does not look too realistic but a global light for the whole scene
would be too expensive. At the back of the thrusters you can see three Empties which generate the exhaust of
the engines using a AddObject Actuator. Similar in front of the ship are two Empties attached which will act
15/02/2011 12:39:15
85
Subracer
as guns.
Ship setup
1 'langle Mesh
- Compound
1
Add Property
DC
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□
Figure [racer-2]. Ship physics and Properties
The physics properties are set to "Rigid Body", so we can have our ship behave correct at collisions and on
gravity. The "Mass:"-field is set to 5 which does give it a higher inertia compared to other objects. You see it
is not always needed to use "real" weights, we more want to make it good looking and good playability rather
than beeing physical simulation. I am using relatively high values for Damp and RotDamp to simulate the
water friction. The ship is set to "Actor", so that Near sensors can see it, this is used for the mines. I also
activated "No sleeping" we don't want to see the ship lazy sleeping on the ground.
We have a bunch of Properties for the ship. The Property "uboot" is just a marker for other objects to filter out
collisions of the ship so that they can react on the collision properly. The other Properties are really containing
values, "turbo", "damage", "head" and "incl" are used to store the values for the functions, for example the
turbo value is used to decide if you still have left enough turbo-fuel to use the turbo. The value is also passed
to the HUD to be displayed, "next" contains the number of the next gate you need to pass, "time" is a timer
and the value is stored into "roundtime" every time you complete a race round correctly. The number of
rounds are counted in the Property "round".
As you can see in figure [racer-3] there are quite a bunch of Logic Bricks involved. However not quite as
much as in a more complete character setup like in the "Yo Frankie!" game.
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Figure [racer-3]. Logic Bricks
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Subracer Sensors
Sensors
Most of the Sensors are Keyboard Sensors to control the ship. Then there are two Collision Sensors to detect
collisions with other objects and a Ray Sensor which detects other objects in range and is used to play a sonar
sound. The two Message Sensors are reacting on messages if new turbo-fuel is found and when the ship
passed a gate. You can see at "GateMess" that I decided not to let the ship detect a pass through a gate but let
the gate detect it and then notify the ship. This is just a matter of taste but will certainly reduce the complexity
of the ship logic. In a multi player game this would also open the way to use the messages to compare the
players ships and to stat the success.
Controllers
Most of the Controllers are just simple AND Controllers and they just pass the pulses to the Actuators because
they only have one input connected. At second position there is a NAND Controller, used to fire a Motion
Actuator when the Forward Key WKEY is not pressed, I will come back to this topic later. There is one
simple Expression Controller "TurboQ and turbo>0.0" which will only allow to use turbo-boost if there is
enough turbo fuel left.
Last but not least we have four Python Controllers. Some of the functionality in these scripts could have been
done with just Logic Bricks, but this would have resulted into a quite complex and hard to maintain logic. But
some of the functions in the scripts are just impossible to do with Logic Bricks, like the calculation of the
angle to the next gate. The scripts "Gun" and "Exhaust" are just simple scripts to add bullets and exhaust
"particles" but overcome a limitation of the AddObject Actuator. The other scripts are a bit more complicated,
it would have been possible to combine them into one script but this also results into a hard to maintain big
script.
Actuators
□
Figure [racer-4]. Logic Bricks to drive the ship
Most of the Actuators are just Motion Actuators directly connected to the Keyboard Sensors to move and
rotate the ship. There is also an Actuator called "Buoyancy" which is used to add some uplift to the ship so
that it will not follow the gravity too fast.
The Actuators to get the ship going are using the new "Servo Control" Actuators. These will bring the ship to
the wanted speed using forces, this will lead to a maximum top speed without caring for problems with
collisions or damping. Using the "Limit Y" in the "Fwd" Actuator we can also control how fast the ship can
accelerate. The "StopSlide" Actuator will prevent the ship sliding sideways (along the ships X-axis) to much,
which would make the control of the ship almost impossible. This simulates (roughly) the water dynamics (as
in aerodynamics) in reality where a ship has less drag along the center line and much drag caused by fins etc.
at the cross axis.
15/02/2011 12:39:15 87
Subracer
Actuators
The Property Actuators are adding to the turbo and damage Properties. The Message Actuators are passing
information to the Cockpit and HUD overlay scenes.
Guns
As I told you above we have two Empties parented to the ship which form the guns of the ship. The exhaust of
the turbines is done in a similiar way.
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As you can see a Keyboard Sensor on the ship (object "UBoot") is connected to a Python Controller (see
Listing [racer-gun]) and the Controller connects with one Edit Object 'Add Object" Actuator on every gun
Empty.
# Gun script
# This script takes the velocity of the ship into account for firing the cannons
# also uses instantAddOb ject to prevent 1 frame lag of the Add Object Actuator
import GameLogic
cont = GameLogic . getCurrentController ( )
me = cont . getOwner ( )
fire = cont .getSensor ("Fire")
gl = cont .getActuator ("Gl")
g2 = cont .getActuator ("G2")
if f ire . isPositive ( ) :
ys = me. getLinearVelocity ( 1 ) [1]
gl . setLinearVelocity (0, 30+ys, 0)
g2 . setLinearVelocity (0, 30 + ys, 0)
gl . instantAddOb ject ( )
g2 . instantAddOb ject ( )
Listing [racer-gun] . Script driving the guns
So why do we use a Python script here? There are two reasons:
1. The Add Object mechanism leads to at least one frame lag or delay, that is not visible (the lag is
visible for the exhaust) but can lead to the situation that the ship, especially when moving quite fast,
runs into it's own bullets.
2. We can give the bullets a initial speed which is the same as the ship has and adds to the bullet speed
We use the function A'A'instantAddObj()A'A' (lines 18-19) to avoid the lag of the Actuator. This function
calls the Actuator immediately and adds the object given in the Actuator (here the object "part" which needs
to be in a hidden layer). The object will have a life-time of 200 frames as entered in the "Time:" field.
In line 15 we get the actual ship speed in forward direction and add that speed in lines 16-17 to the desired
bullet speed of 30. The function A'A'setLinearVelocity()A'A' set the speed like the input fields "linV" in the
15/02/2011 12:39:15
88
Subracer
Actuator.
Guns
Game Objects
Turbo crate
The logic for the turbo fuel crates is quite simple. The upper row of logic bricks is just for rotating the box.
When an object with the Property "uboot" collides with the box (which has the "Ghost" physical property to
avoid any restitute) a message is send which tells the ship that it got 100 "liter" turbo fuel, and then the crate
object is deleted from the scene (End Object).
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So why is the crate also deleted when a message with the subject "Init" is received? We need to make sure
that in every race round new crates are there, so on a init or game start we delete all left over crates and the
add new ones, which leds us to the logic on how we add these crates.
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You can see, it is just an Empty placed everywhere in the level where a turbo-crate should be. At game start
and when a round is completed an "Init" message is send, which causes all existing crates to vanish and new
ones created at the Empties. This can work because there is a lag or delay of one frame in between receiving
the message and creating new objects, that way the init message can't destroy the new created objects.
Mine
15/02/2011 12:39:15
89
Subracer
Mine
□
The mine is made up from a few objects, the mine itself, two pieces of chains (so they can be animated
moving in the waves) and the anchor block. The logic for the mines are basically just a Near Sensor which
works as a proximity fuse, it only reacts for objects with the "uboot" Property. So what happens then?
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First of all an explosion sound is played, then we remove the mine and the chain objects, the lower chain is
replaced (using an Edit Object Actuator type "Replace Mesh") by a mesh of a chain laying on the ground.
Then an object with the fireball is added and an object which builds the Shockwave.
The Shockwave object is just a textured sphere which scales up quickly and any physical object in range will
be blown away by the sphere. If you give the sphere a Property "uboot" and make the sphere big enough you
can produce nice chain reactions.
Gate
15/02/2011 12:39:15
90
Subracer Gate
□
The gates in the game have a quite simple logic. If you look at the Logic Bricks (I removed the LBs to rotate
them here) you can see that the logic again is spreaded on different pails of the gate. The gate itself has an
Always Sensor, a Python Controller and a Message Sensor. Interconnected are a Always Sensor from the gate
number display and a Collision Sensor from the green "energy" surface.
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The "Ink" Sensor fires one time at game start and then the script is used to register the gate to a global
variable (lines 15-23). After game start, all gate-objects are then stored into a Python Dictionary where they
can be accessed by their names. Beside that, the gate number display is filled with the current gate name.
# This handles the gates
import GameLogic
me = GameLogic . getCurrentController ( ) .getOwner ()
cont = GameLogic . getCurrentController ( )
init = cont . getSensor ( " Init " )
nr = cont . getSensor ( "Nr" )
through = cont . getSensor ( "Through" )
gate = cont . getActuator ( "GateMess" )
# the (random number) of gates are registering themselves into a global variable
# be shure to name the gates Gate . 000 ... Gate .XXX in the correct order!
if init . isPositive ( ) :
# set the visible gate name
nr . getOwner ( ) . Text = me . name [2 : ]
try :
GameLogijates [me . name] =me
except :
# first gate?
GameLogijates={ }
GameLogijates [me . name] =me
# ship has passed the gate, send message to the ship
if through . isPositive ( ) :
gate. setBody (me . name)
GameLogic . addActive Actuator (gate, 1 )
Listing [racer-gate]. Gate's init script
When the ship (or any object with the "uboot" Property) passes the energy surface object inside the gate
("Ship Sensor") a message with the name of the gate is send in lines 26-29. This message is then used by the
ship scripts to determine which gate is next and to count rounds and time.
15/02/2011 12:39:15
91
Subracer
GLSL Mist
GLSL Mist
To achieve a nice underwater look with dimminishing blue colors for objects further away it is possible to use
the standard mist in the World Buttons. With some tweaking this really looks nice. However, the standard
mist has the disadvantage that it works not well together with faces set to "Add" and also shows some
problems with alpha-faces. This is the reason I decided to use GLSL-mist, which is in fact just a
Node-material. Further to the compatibility with "Add"-faces, it is also possible to make multi-color mist and
other advanced stuff, on the "Yo Frankie!" DVD Pablo explains in a tutorial how to do this. Another
advantage is that you can exclude objects from the mist.
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□
The mist is a Node group named "Mist" which you can append to your own scenes.
To use Node materials you can first set up all your materials as you are used to do. Then activate the "Nodes"
Button in the Material Buttons F5, "Links and Pipeline"-panel.
□
Next change one window to a Node Editor and chose your base material in the Input Node. When you now
render with F12 or start the game with PKEY nothing has changed, but in fact we are now using the Node
material system. Now back in the Node Editor cut the wire between Input and Output Node and add the Mist
group which you appended from the scene on the book disk.
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15/02/2011 12:39:15
92
Subracer
GLSL Mist
Connect the yellow Color connections from Input to the "Misf'-Group and then to the Output Node. The
effect should be visible immediately in the 3D View when you have activated "GLSL Materials" in the
"Game"-menu
This procedure you have to repeat for all materials which should be affected by the mist.
When you open the "Misf'-Group you can see how this effect is achieved. The strength of the mist should be
dependent from the distance camera to object, a farther away object will become more blue (or other colors
for other types of mist). This distance we get from the "Camera Data" Node, "View Distance". Of course this
distance can be quite big and depends on the overall scene scale, so we most probably need to scale it to our
needs, which is done by the "Mapping "-Node. Notice the "O.OIA'A' at the third place (Z coordinate) in the
"Size" row, this means that the view distance value is divided by 100. So why "Z"? This is because the
cameras in Blender always look along their Z-Axis.
Next we pass the value through a "Color Ramp"-Node which will clip the value to a range between and 1 .
and can also be used to fine tune the mist appearance. Next we mix the original color of the material (Color 1)
with a blueish color (Color2) coming from a "RGB"-Node with the "Mix"-Node. The amount of mixing is
controled (Fac) by the value derived from the view distance. And thats it!
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For the best effect you should set the color of the world to exactly the same color as in the RGB Node. To
achive this just pick the color from the RGB Node with the "Sample"-tool of the color-picker in the World
Buttons.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15
93
Blender Basic Network setup - Boil it down to the
basics
by aOld Jima Coulter
Making games and playing them is a lot of fun, but it is even more fun if you can make games to play
together with your friends. I will show you how to acooka a basic network setup in blender. Since
Blenders game engine has no build in network support we have to do it in Python, for this you need a
matching Python installation for Blender. Take a close look at the terminal or dos-box output when
Blender starts, it will tell you which version it needs and if the import worked.
Ingredients
IP: Unique Computer name
LAN IP: Only accessible inside the local network
Internet IP: Accessible form all over the world (when routers and firewalls allows it)
Port: Access line to a specific communication
Socket: Transmitting and receiving station.
Libraries: Importing cookbooks (modules) from the Python Library gives blender info on how to
prepare a special meal
Logic Bricks: central switching station of the Blender game engine.
Objects: We will use 2 cubes which we can move around and these movements we will send over the
Network.
If you load the file BasicNetwork.blend you can find 2 scripts in there which are relevant to our
network setup. (Server.py and Client.py). These scripts show what you get if you boil a network
down to its basics. So what do they do?
Server.py
Script
1. # SETUP #
2. from GameLogic import *
3. from socket import *
4. from cPickle import *
5. cont = GameLogic . getCurrentController ( )
6_ obj = cont . getOwner ( )
7, if obj.OneTime == 0:
3_ ServerIP = GameLogic. IP
9_ Serverport = 10000
10. Clientname =
11. ClientPort = 10001
12. GameLogic. sClient = socket (AF_INET, SOCK_DGRAM)
13. GameLogic . sClient . bind ( (Clientname, ClientPort ) )
14. GameLogic . host = (ServerIP, Serverport )
15/02/2011 12:39:15 94
Blender Basic Network setup - Boil it down to the basics Script
15. Game Logic .sClient.setblocking(O)
16. obj.OneTime = 1
17. PosYou = ob j . getPosition ( )
1§_ scene = getCurrentScene ( )
19. Server = scene . getOb jectList ( ) ["OBServer"]
20. PosServer = [0,0,0]
21. # RECEIVE/ SEND #
22. Data = dumps ( (PosYou) )
23. GameLogic . sClient . sendto (Data, GameLogic . host )
24. try:
25. Data, SRIP = GameLogic. sClient . recvf rom (1024 )
26. UPData = loads (Data)
27. PosServer = [UPData [0] , UPData [1 ], UPData [2 ] ]
28. Server . setPosition (PosServer)
29. Server . setOrientation ( Or i Server)
30. except :
31. Pass
Explanation
from GameLogic import *
From the library we import the book (module) called GameLogic. By importing this book we have
access to all the information about the blender game engine.
from socket import *
Gives us all the information about network socket setups.
3:
from cPickle import *
Gives us information on how to pack data in to a container (similar to a zip program).
4:
cont = getCurrentController ( )
This command gets the Controller for the script and saves it to the variable cont. The logic brick we just made
accessible, is the Controller that gave the order to execute the python script.
5:
Obj = Cont . getOwner ( )
Gets us the owner of this script. That would be the object that owns the logic brick.
6:
if Obj.OneTime == 0:
12:
15/02/2011 12:39:15 95
Blender Basic Network setup - Boil it down to the basics Explanation
Obj .OneTime = 1
Line 6 calls up the property OneTime and if its value is equal to it will execute the lines below that are
indented. Line 12 will change the value of the property OneTime to 1. By changing the property
we make sure that the indented lines below line 5 only run one time.
7:
host = ' '
Saves a empty text holder in to the variable host. The purpose of this empty text holder is to make a place
where later the computer name can be written in to. So you may ask; why not write the computer name in to it
right away? Well you could do that but then this script would only run on your own computer. So thatas
why we leave it empty and let the socket fill it out later all by it self. You also
would have the option to write localhost between the aa, that would say the script right a way to enter
the name of the local computer in therea! But why write more then necessary?
ServerPort = 10000
Saves the value 10000 in to the variable ServerPort. This value will be the port number over witch the socket
will communicate. Thatas why you will have to make sure that your firewall and your router wonat
block this and the other ports that will be added later. Information on how you can setup your firewall and
router to forward information over this port, can be found in the manuals of your firewall and router. If any
questions or problems come up then you can ask them in the gameblender.org forum.
GameLogic. sServer = socket (AF_INET, SOCK_DGRAM)
This code will create a socket that uses the protocol that is defined inside of the brackets and saves it to the
global variable GameLogic. sServer.
AF_INET,SOCK_DGRAM is the definition for the UPD protocol. We will use this protocol because it is very
fast and will keep on working even if it once canat send or receive a packet.
10:
GameLogic . sServer . bind ( (Host, ServerPort ) )
The code .bind((host,Serverport)) is used to bind the information that we have saved in to variable host and
Serverport to the socket. Now the socket knows on what computer and over witch port he should
communicate.
11:
GameLogic . sServer . setblocking ( )
The socket will already work with the lines above. But as I already mentioned by line 8 we would like to
make sure that the script will keep on running even if the socket did not send or receive a packet.
This can happen very easy, if the connection having a problem, the client and server have different streaming
rates the connection is temporary used by a other programa! Thatas why we will use the
code .setblocking(O). The in the brackets will tell the script that it should not block even if it did not send or
15/02/2011 12:39:15 96
Blender Basic Network setup - Boil it down to the basics Explanation
receive anything. If you would put a 1 there, the script would try to receives/send a packet until it has had
success. If you would do this everything would be as slow as the slowest client that is connected with the
server.
13:
PosYou = ob j . getPosition ( )
Gets the position of servers cube (the server controls the blue cube)
14:
scene = getCurrentScene ( )
15:
Client = scene. getOb jectList () ["OBClient"]
The command getCurrenScene() will get all the elements of the current scene in to the script. These elements
will be saved in the variable scene. The variable scene contains all the elements of the current scene, now we
would like to have access to all the Objects in the scene, this will happen by using the command
.getObjectList(). In the square brackets we write the name of the object that we would like to save to the
variable objPumpl. Its important that you put the letters aOBa in front of the objects name.
16:
PosClient = [0, 0, 0]
In the variable PosClient we provide a list with 3 elements. This list will be later filed with the coordinates of
the player. The 3 elements [0,0,0] stand for the X, Y and Z coordinates.
17:
try :
Line 17 starts to try to execute the indented lines below if one of the lines fail lines 24 and 25 come in to
action telling the script to just pass on. The only line below that actually can fail is the Line 18. It
will fail when it tries to receive and there is no data there to receive. This can for example happen if no Client
is sending any data.
18:
Data, CLIP = GameLogic . sServer . recvf rom ( 1024 )
The variable GameLogic. sServer contains the information about the socket. The code .recvfrom commands
the socket to receive data. (1024) defines the maximal size, that the buffer can receive at once. Every time we
receive data we get 2 blocks. The first block contains the data and is saved in the variable Data. The second
block contains sender address and is saved in the variable CLIP (=Client IP)
19:
UPData = loads (Data)
Now we will use the methods from the cPickle module for the first time. The received data will be unpacked
and saved to the variable UPData, As you will see in line 22, data that is send over the network is first packed
in to a container.
15/02/2011 12:39:15 97
Blender Basic Network setup - Boil it down to the basics Explanation
20:
PosClient = [UPData [ ] , UPData [1 ] , UPData [2 ] ]
The received und now unpacked data is saved in to the list we made in line 16.
UPData[0] = Position on the world axis X
UPData[l] = Position on the world axis Y
UPData[2] = Position on the world axis Z
21:
Client . setPosition (PosClient)
The list we just have filed out is now used to set the position of the clients player.
22:
Data = dumps ( (PosYou) )
The command dumps will pack any data inside the double brackets in to a container and save it to the variable
Data. Important: You have to use double brackets here a((PosYou))a and not single brackets
a(PosYou)a. The Variable PosYou that we are packing here contains the information of the coordinates
of the Server cube (blue) see line 13.
23:
GameLogic . s Server . sendto (Data, CLIP)
To send Data we use GamLogic.sServver to call up the socket and give it the command .sendto. To send data
do it just as in line 18, you need 2 things: The data and the address that this packed should be send to. This
information you put inside the brackets.
24:
except :
25:
pass
These lines work together with line 17 and already where explained.
The client script.py is very similar to the server.py script, the only real difference is that it sends data to the
server first, so it dose not have an already received package that contains the servers address; so this will have
to be entered manually. We do this in the script setup.py line 10. By entering the servers IP address there
behind the global variable GameLogic.IP. If you now study the script below you may say he way not just
write it in to line 7 instead of putting the global variable GameLogic.IP there. You are right, you can do so but
by having the IP entering in the setup.py script it makes it easier to find it.
Also the setup.py script contains other informations that help a user to start this program in any network. See
lines that are behind a comment mark a#a. They are not part of the script, but give you information on
how to use this script. So thatas why we will have the 3D window on the left side and the setup.py script on
the right side when we open the Basic Network.blend file.
15/02/2011 12:39:15 98
Blender Basic Network setup - Boil it down to the basics Client. py:
Client.py:
Script
1, # SETUP #
2, from GameLogic import *
3, from socket import *
4, from cPickle import *
5, cont = GameLogic . getCurrentController ( )
6. obj = cont . getOwner ( )
7. if obj.OneTime == 0:
8. ServerIP = GameLogic. IP
9_ Serverport = 10000
10. Clientname =
11. ClientPort = 10001
12. GameLogic. sClient = socket (AF_INET, SOCK_DGRAM)
13. GameLogic . sClient . bind ( (Clientname, ClientPort ) )
14. GameLogic . host = (ServerIP, Serverport )
15. GameLogic . sClient. setblocking(O)
16. obj.OneTime = 1
17. PosYou = ob j . getPosition ( )
18. scene = getCurrentScene ( )
19. Server = scene . getOb jectList ( ) [ "OBServer " ]
20. PosServer = [0,0,0]
21. # RECEIVE/ SEND #
22. Data = dumps ( (PosYou) )
23. GameLogic .sClient . sendto (Data, GameLogic . host )
24. try:
25. Data, SRIP = GameLogic. sClient . recvf rom (1024 )
26. UPData = loads (Data)
27. PosServer = [UPData [0] , UPData [1 ], UPData [2 ] ]
28. Server . setPosition (PosServer)
29. Server .setOrientation ( Or i Server )
30. except :
31. P ass
Explanation
Since all the commands in this script where explained in the server.py script I will only give a short summary
on these lines of code.
Lines 1 a 5:
Basic setup to access the Object, its properties and logic bricks.
Lines 6 + 15:
Make sure that the intended lines below Line 6 only run once.
Line 7:
Saves the global Variable that contains the IP to a local Variable.
Lines 8 a 12:
Setup the Socket
15/02/2011 12:39:15 99
Blender Basic Network setup - Boil it down to the basics Explanation
Line 13:
Saves the complete Server address to a variable.
Line 14:
Tells the script to just keep running even if no data was send/received.
Line 16:
Gets the position of the red cube.
Line 17+ 18:
Make the blue cube accessible by this script.
Line 19:
Makes a empty list, that will be uses to set the servers cube (blue cube)
Line 20 + 21:
Packs your position in a container and sends it to the server.
Line 22, 28,29:
Will try to run the intended lines below line 22, if they fail the script will just pass on.
Appetite for more
I hope this little starter whetted your appetite for more. There is a more complete tutorial on the DVD
(Blends/WSAGNetwork/PumpkinRun_MP.blend) and a lot of information about more complex network
"meals" can be found at www.wsag.ch.vu . If any questions come up you can ask them at the gameblender.org
forum.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
15/02/2011 12:39:15 100
Game Character Animation using Armatures
by Reevan McKay
The armature system opens up many possibilities for character animation in the Blender game engine, but can
be somewhat intimidating for new users. This tutorial guides you through the steps involved in building an
armature and creating actions that can be used for smooth character animation in the game engine.
Preparing the Mesh
This tutorial assumes you have already modeled a character that you want to use in an animation. Due to the
high cost of calculating skeletal deformation, you will get better performance by using fewer vertices in your
meshes. It pays to spend some time to optimize your models before continuing. You can use the file
Tut or ials/ Char act er Animation/ Char act eranimOO .blend as base for this tutorial.
Many aspects of blender's game and animation engines depend on the fact that you have modeled your
character and armature using the correct coordinate system. The front view (PAD1) should show the front of
your character and armature. If this is not the case, you should rotate your mesh so that the front of the
character is displayed in the front view, and apply the rotations as described in the next step.
Before adding bones and animating a mesh, it is a good idea to make sure that the base mesh object does not
have any rotation or scaling on it. The easiest way to do this is to select the mesh and apply any existing
transformations with CTRL-A->"Scale and Rotation to ObData".
Working with Bones
The next step is to build the skeleton or "armature" that will be used to deform the character. A single
armature object can contain an entire hierarchy of bones, which makes editing animations easier. Select your
character, then position the 3D-Cursor on it using SHIFT-S->"Cursor to Selection". Add an armature object
from the toolbox by pressing SPACE->A->" Armature".
You will see an Armature with one bone appear. Armatures have an Edit Mode similar to meshes. As with
meshes, you can toggle in and out of Edit Mode using TAB. While you are in Edit Mode, you can add and
remove bones, or adjust the rest position of existing bones. The rest position of your armature should
correspond to the untransformed position of the mesh you want to deform, and you should build the armature
inside the mesh, like a skeleton inside a human body.
□
While you are in Edit Mode, you can reposition a bone by selecting one or more of its endpoints and using the
standard transformation tools such as scaling (SKEY), rotation (RKEY) and translation (GKEY).
You can also extrude selected points to form new bones with EKEY.
Now enter Edit Mode and select the tip of the bone. Move the tip to the position showed in figure [c-add] .
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Game Character Animation using Armatures
Working with Bones
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Figure [c-add]. Adding bones
Now click with LMB to the place where the tip of the new bone should be. At this point a new yellow bone
will appear, attached to the end of the first bone. You can continue to add connected bones in this fashion. If
you do not want to create another bone, you can press ESC to cancel the current (yellow) bone. The bones you
added previously will not be affected.
One or more bones can be selected by selecting their start and end points. Like meshes, you can select all of
the bone points within a region by using BKEY or you can select or deselect all bones in an armature with
AKEY. You can also select an entire bone chain at once by moving the mouse over any one of the chain's
points and pressing LKEY. Selected bones can be deleted with XKEY or duplicated with SHIFT-D.
Creating Hierarchy and Setting Rest Positions
Naming Bones
Editing Options
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It is a good idea to give meaningful names to the bones in your armature. This not only makes it easier to
navigate the hierarchy, but if you follow a few simple naming rules, you can take advantage of the
pose-flipping features. You can have the bone names displayed on the model by selecting the armature,
switching to the Edit Buttons F9 and clicking the green "Names" button in the "Armature"-panel.
For symmetrical body elements such as arms or legs, it is a good idea to append ".left" or ".right" (or simply
".1" and ".r") suffixes to each part. This information is used when flipping poses. An example of this would be
to name the right arm "Arm.Right" and the left one "Arm.Left". Non-paired limbs such as the head or chest do
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Game Character Animation using Armatures
not need any special naming.
Naming Bones
When re-using the same action on different armatures, the engine looks at the names of the bones in the
armature, and the names of the animation channels in the action. When there is a perfect match (capitalization
matters), the animation data in the action will be applied to the appropriate bone. If you want to take
advantage of action re-use, make sure that all your skeletons use the same naming convention.
Parenting Bones
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□
To establish parenting relationships within an armature, you must first make sure the armature is in Edit
Mode. Now select the bone(s) you with to be the child, then the parent bone with RMB. Now press CTRL-P
to call the "Make Parent" menu. Here you can choose if the child-bone should be just parented (Keep Offset)
or be connected to the parent. In the later case the the child bone will be moved so that its root matches to the
tip of the parent. To remove parent relations use ALT-P.
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If you named all the bones properly there is also another way to handle parent relations: Select the bones you
wish to modify (or if you prefer, select all bones with AKEY) and switch to the Edit Buttons with F9. You
will see a list (Figure [c-list]) of the selected bones in the "Armature Bones"-panel and next to each bone in
the list you will see a "child of" label and a pull-down menu. To make a bone the child of another bone,
simply select the appropriate parent from the pull-down menu. Note that the menu only contains the names of
bones that could be valid parents. This prevents you from accidentally making a loop in parents (such as
making an arm the parent of the chest, which should be parent of the arm).
To clear a parenting relationship, set the "child of" menu to the first (empty) choice in the menu.
Parenting is much easier if you have already named your bones, though it is not necessary.
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Game Character Animation using Armatures
Basic Layout
Basic Layout
□
Figure x-y. Typical bone layout for a humanoid character
For a typical humanoid character, the following hierarchy is recommended. Some characters may benefit from
additional bones for elements such as flowing skirts or hair.
Coordinate System Conventions
Before going on, it is a good idea to clear any rotation or scaling that may have been assigned to the armature.
Leave Edit Mode and with the armature object selected, apply the transformations with CTRL-A->"Scale and
Rotation to ObData".
The center point of the armature (represented by a purple dot) should be located on the ground, between the
character's feet. If this is not the case, enter Edit Mode for the armature, select all bones with AKEY and move
the bones so that the center point is at the correct location.
The final step before preparing the mesh for deformation is to ensure that the bones in the armature have
consistent orientations. Each bone is like an individual object with its own coordinate system. You can see
these coordinate systems (in Edit Mode) by selecting the armature object, switching to the Edit Buttons with
F9 and clicking on the green "Draw Axes" button in the "Armature"-panel.
Generally you want to make sure that the Z-axis for each bone points in a consistent direction. In most cases
this means having the Z-axis point upwards. You can adjust the roll angle of a bone by selecting it in Edit
Mode, pressing NKEY and adjusting the "roll" field.
If you are going to be re-using actions on different armatures, it is very important that both armatures have
their bones oriented in the same way. If this is not the case, you will notice a lot of strange flipping happening
when you assign the action.
Establishing Mesh Deformation Vertex Groups
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Game Character Animation using Armatures
Creating Groups
Creating Groups
Once your armature is established, it is time to specify which bones will affect which vertices of the mesh.
This is done using vertex groups.
Attaching the Mesh to the Armature
At this point, we should attach the mesh to the armature. Make sure that the mesh and the armature are
correctly lined up and that you are not in Edit Mode.
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Select the mesh first and while holding SHIFT, select the armature and press CTRL-P->"Use Armature".
Blender now asks if he should create vertex groups automatically for you.
There are different options:
Don't Create Groups: no groups are created, use this if your character already has groups or you like to keep
total control on the whole process.
Name Groups: create groups with the names of the bones, there are no vertices in the groups!
Create From Envelopes: create groups and assign all vertices to them lying in the range of the bones
envelope
Create From Bone Heat: an attempt to assign vertices automatically to bones. This will often lead to a nice
starting point for further work
For editing and refining the groups you can assign vertices to the currently active deformation group by
selecting vertices and clicking the "Assign" button. The selected vertices will be assigned to the active group
with the weight specified in the "Weight" slider. You can remove vertices from the current deformation group
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Game Character Animation using Armatures
by selecting them and clicking the "Remove" button.
Testing the Skinning
If you prefer the total control of the process, create vertex groups for all of the bones in your armature
(making sure the names of the groups and bones match) and assign vertices to the appropriate groups. Make
sure that every vertex is affected by at least one bone. For this "first pass" of the deformation process, try to
keep things simple by leaving the weight set to "1.000" and avoid having vertices being assigned to more than
one group.
Vertex Groups
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□
To access the vertex grouping features, select the mesh you will be deforming and enter Edit Mode. Switch to
the Edit Buttons and find the "Group" column. Normally you will have one vertex group for each bone in the
armature. A vertex can belong to more than one group, which is how smooth deformation is achieved. In
order to be recognized by the armature, the vertex groups must have exactly the same names as the bones they
are associated with (capitalization matters). To create a new vertex group, click on the "NEW" button and edit
the name in the text button that will appear.
You can see a list of all of the current deformation groups by clicking on the menu next to the group name
button. Selecting an item from this menu changes the active deformation group.
Testing the Skinning
Once you have attached the mesh to the armature, you are ready to start testing the deformation. It often takes
a fair amount of tweaking to get satisfying results. You want to avoid the excessive pinching or stretching that
can occur when vertices are not assigned to the right bones. We'll spend more time on that later. For now,
we'll take a look at how to pose the armature, which is a skill needed for testing the deformation.
Pose Mode
In addition to Edit Mode, armatures have a Pose Mode. This is used to position bones within the armature.
Setting key frames in Pose Mode defines an "action" for the armature, and the game engine will use these
actions to animate the character.
Note that only transformations performed in Pose Mode will be incorporated into the action (and therefore the
;ame engine). Rotations, scalings and translations performed in Object Mode cannot be recorded in actions.
Figure x-y. Armature in Pose Mode
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Game Character Animation using Armatures
Pose Mode
You can toggle in and out of Pose Mode by selecting an armature and pressing CTRL-TAB or by selecting
Pose Mode with the mode-menu in the 3D View header. When in Pose Mode, the armature will be drawn in
blue, with selected bones drawn in a lighter shade.
To manipulate bones in Pose Mode, select bones by using RMB on them and use the standard transformation
keys for scaling, rotation and translation. Note that you cannot add or remove bones in Pose Mode, and you
cannot edit the armature's hierarchy.
At any time, you can clear the pose you have made and return to the armature's rest position by clearing the
rotation, scaling and translation components using ALT-R, ALT-S and ALT-G respectively.
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Figure x-y. Insert a key for "Arm.L" and "Bicep.L" bone
You can set key frames for a pose by selecting one or more bones and pressing IKEY and choosing one of the
transformation channels to key from the pop up menu.
Weight Editing
In Pose Mode, manipulate the limbs of the armature through their typical range of motion and watch carefully
how the mesh deforms.
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Game Character Animation using Armatures
You should watch out for deformation artifacts caused by any of the following:
Weight Editing
□
• Vertices that are not assigned to any bones can be easily detected by moving the root of the
character's hierarchy (usually the hips or pelvis) and seeing if any vertices are left behind.
• Vertices that are not connected to the correct bones. If you move a limb (such as the arm) and notice
vertex "spikes" protruding from other parts on the body, you will have to enter Edit Mode for the
mesh and remove the offending vertices from the vertex group.
• Pinching or creasing caused by inappropriate vertex weighting. This effect is most visible in the joints
of limbs such as arms and legs. Often it is a symptom of vertices that are members of too many
groups. The easiest way to fix this is to use the weight painting tool.
To adjust vertex weights, you have the choice of manually assigning weights using the method outlined
above, or you can use the weight painting tool.
□
Figure [c-wp]. Weight painted character
This feature lets you "paint" bone influence onto the mesh and see the resulting deformation in real-time.
Make sure you are in wireframe or untextured mode with ZKEY or SHIFT-Z. Access weight painting mode
by selecting the mesh and clicking on the weight-paint icon in the 3D View header.
In weight paint mode the mesh is displayed with a "false color" intensity spectrum similar to the view from an
infrared camera (Figure [c-wp]). Blue areas have little or no influence from the current deformation group
while red areas have full influence. As you change the active deformation group in the Edit Buttons F9, you
will see the coloring on the model change.
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Game Character Animation using Armatures
Animation
Painting weights onto the model works somewhat similarly to vertex painting. LMB paints onto the area
beneath the cursor. Pressing UKEY undoes the last painting operation. The cursor size and opacity settings in
the Vertex Paint Buttons are used to determine your brush settings and the "Weight" field in the Edit Buttons
is used to determine the "color" you are using (0.000 is the blue end of the spectrum and 1.000 is red).
To remove weight from a group of vertices, set the vertex weight to 0.000 and paint over the area. Note that
you do not need to have the mesh in Edit Mode to change the active deformation group, or to change the
weight.
Animation
Animation is very important for conveying the impression of life in a game world, and for giving the player an
immediate reward for his or her decisions. Game characters typically have a set of animated actions they can
perform, such as walking, running, crawling, making attacks or suffering damage. With the armature system,
you can design each animation in a separate action and define which actions play at which times using Logic
Bricks.
At the time of writing, animation constraints (including the IK Solver) only work in the game engine as long
as you use loose bones in the Armature as targets for the constraints. Enter the armature name into the OB :
field, then a BO: field appears where you can enter the desired bone name. Another help is provided by the
use of "Auto IK" in the "Armature" -panel which will help you in posing.
Multiple Actions and Fake Users
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□
Figure [c-db]. Structure of the file in the Data Select Window
If you want to create multiple actions in a blender file, remember that only one action can be assigned to an
armature at a time. If the other actions do not have any users, they will not be saved when the file is saved. To
prevent additional actions from disappearing a fake user is automatically added to Actions.
To create or remove a fake user for an action, press SHIFT-F4. This lets you browse the various objects and
data blocks in the blender file. You may need to click on the "P" button once or twice to find the root of the
file's structure, which should look like Figure [c-db]. From there, descend into the Action directory, and select
the actions you want to protect or unprotect with RMB. Pressing FKEY will add or remove a fake user to the
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Game Character Animation using Armatures Multiple Actions and Fake Users
selected items (indicated by the capital "F" that appears next to the action name), preventing them from being
accidentally removed from the file.
Creating an Idle Cycle
The simplest action to create for a character is the "idle" or "rest" position. This action can be played when the
character is not doing any other action. A good idle animation gives the game character the illusion of life by
keeping it moving even when the player is not actively issuing any control commands.
Since the character is not moving through the level while playing the idle animation, we don't have to worry
about syncing the animation with the physics system.
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To create a new action, split the view by clicking with MMB on one of the window borders, selecting "Split
Area", and LMB to set where the split will appear. Change the type of the newly created window to Action
Window by LMB on the window-type icon in the Header and choosing the Action icon.
Go to a 3D View and select the armature you wish to animate. Enter Pose Mode and make sure that Blender is
on frame 1 by changing the number in the frame counter button in the header of the Buttons Window, or by
using SHIFT-LEFT.
You are now ready to make the first frame of the idle animation, using the Pose Mode techniques described
earlier. What this pose looks like will depend largely on the personality of your character and the type of game
you are making. Consider which actions might immediately follow the rest position. If the character is
supposed to be able to fire a weapon quickly, the rest position might involve holding the weapon in a
ready-to-fire stance. A less fast-paced game might have the character adopt a more relaxed "at-ease" pose.
When you are satisfied with the first frame, select all of the bones in Pose Mode and insert a rotation key by
pressing IKEY->"Rot". Next, deselect all bones and select only the character's root bone (usually the pelvis or
hips) and insert a "Loc" key. Normally only the root bone gets location keys, while all bones get rotation keys.
When you insert keys, you should notice that new channels appear in the action window (Figure [c-fk]). The
yellow rectangles represent selected key frames and gray rectangles represent unselected key frames. You can
move key frames in the action window by selecting them and grabbing them with GKEY.
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Game Character Animation using Armatures
Creating an Idle Cycle
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□
Figure [c-fk]. Keys in the Action Window
Key frames can be deleted by selecting them and pressing XKEY->"Erase selected".
You can erase an entire action channel (all key frames for a particular bone), by selecting one or more action
channels by SHIFT-RMB on the channel names in the column at the left. Selected channels are displayed in
blue, while unselected channels are displayed in red. Pressing XKEY->"Erase selected channels" with the
mouse over the channel list deletes the selected channels.
In order to create an action that loops smoothly, you will need to copy the first frame and duplicate it as the
last frame of the animation. There are two main ways of doing this.
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□
• The first way is to select all of the bones in Pose Mode and click on the "Copy Pose" button. This will
copy the transformations from the selected bones into a temporary buffer. You can paste the pose at
another keyframe by changing the frame and clicking the "Paste Pose" button. Note that this doesn't
necessarily set key frames at the new point in time, unless you have activated the "Auto Keying"
option in the preference window. If you have not activated "Auto Keying" and you want to make key
frames after pasting the pose, you can press IKEY-"Avail".
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Game Character Animation using Armatures Creating a Walk Cycle
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□
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• The second way to copy a block of key frames is even easier. In the Action Window, select the
vertical column of key frames for all channels (hint: use BKEY to select with a bounding rectangle).
Pressing SHIFT-D will duplicate the key frames. You can move the block to a new point in the
timeline and drop them by LMB. To ensure that the key frames stay on whole frame increments, hold
down CTRL while dragging.
Idle animations tend to be fairly long, since the motion involved is typically subtle and shouldn't be seen to
loop too often. The last frame should be at least 100 or higher.
While animating, you can "scrub" through the animation by holding the left mouse button and dragging the
mouse in the action window. This will move the position of the green "current frame" indicator. In this way
you can test parts of the animation to make sure they play smoothly. You can also play the whole animation
by moving to the first frame and pressing ALT-A with the mouse over a 3D View. To see the animation in a
loop, set the "Sta" and "End" values in the Display Buttons (F10) window to match the start and end frames of
your loop.
At this point you can go back in and add additional key frames between the start and end. Remember to keep
the motion reasonably subtle so that the player doesn't notice the repetitive nature of the action. Good
elements to add are breathing effects, having the character adjust its grip on any weapons or equipment, and
slight head turns.
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□
When you are satisfied with the action, give it a name by editing the name field in the Action Window
Header.
Creating a Walk Cycle
Another very important action is the character's walk cycle. This animation will be used when the character is
moving through the level. This animation is somewhat more complicated, since we have to consider how the
animation will interact with the physics system.
When creating the walk cycle, it is generally best to animate it in such a way that the character seems to be
walking on a treadmill. The forward motion will be provided by the game's physics system at run time.
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Game Character Animation using Armatures
Creating a Walk Cycle
A walk-cycle actually consists of two steps. One for the left foot and one for the right foot. For each step there
are two main key frames: the striking pose and the crossing pose (Figure [c-sc]). The striking pose represents
the moment when one foot has just been planted on the ground and the other is about to be lifted. The crossing
pose represents the moment when the two legs cross each other under the character's center of gravity: one
foot is on the ground and moving backwards, while the other is lifted and is moving forwards.
□
Figure [c-sc]. Striking and crossing
To start creating this animation, switch to the action window and create a new blank action by clicking on the
Action menu and choosing 'Add New". This will create a copy of any action that may have already been on
the character. Name the action and make sure the animation is blank, by moving the mouse over the channel
list, selecting all channels with AKEY and deleting them with XKEY->"Erase selected channels".
For this animation, we'll make a 24 frame walk cycle. We'll set five key frames to get a basic walking motion
established. Once that's done you can go back and add additional key frames to smooth out the motion and
improve the animation (Figure [c-kf]).
□
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Game Character Animation using Armatures Creating a Walk Cycle
Figure [c-kf]. Key frames for the walk cycle
The first thing to do is to set the striking pose for the left foot. This pose will be copied and pasted as the last
frame of the action to ensure the animation loops smoothly. Note that if you later make changes to this first
frame, you should copy those changes to the last frame again.
The striking pose has the following characteristics:
• The leading leg is extended and the foot is firmly on the floor.
• The trailing foot has the toes on the floor and the heel has just left the ground.
• The pelvis is lowered, to bring the feet down to the level of the floor.
• If the walk cycle incorporates arm swinging, the arms oppose the legs. If the left leg is advanced, the
left arm will be swung back, and vice versa.
When you are satisfied with the pose, insert rotation key frames for all bones, and insert an additional location
keyframe for the pelvis bone. Copy this pose to the end of the animation loop, which will be frame 25. Frame
25 will not actually be played however; we will end the loop at frame 24 when playing. Since frame 25 is a
duplicate of frame 1, the animation should play back seamlessly.
If you built the character's armature using the naming conventions and coordinate systems recommended
earlier in the tutorial, you can take advantage of the character's axial symmetry by copying the striking pose
and pasting it flipped. To do this, go to the first frame, and select all bones in Pose Mode. Click the "Copy
Pose" button and set the active frame to the middle of the animation (in this case, frame 13). To paste the
pose, click the "Paste Flipped" button.
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□
Set "Avail" key frames for the appropriate bones. Note that if your animation does not incorporate arm
swinging (for example if the character is carrying a weapon), you might choose to only select the pelvis and
legs when copying and pasting the pose. Otherwise, the character will seem to switch the weapon from one
hand to the other.
The next task is to create the crossing pose. The first one will occur halfway between the first frame of the
animation and the flipped pose you just created (i.e. frame 7). The crossing pose has the following
characteristics:
• The planted foot is underneath the character's center of gravity.
• The lifted foot is crossing past the planted leg.
• The pelvis is raised to bring the feet up to the level of the floor.
• If the arms are swinging, the elbows will be crossing each other at this point.
Set "Avail" key frames for all bones on this frame and copy the pose. Advance the active frame to halfway
between the end of the animation and the second striking pose (frame 19) and paste the pose flipped.
At this point test your animation loop. It is a good idea to go in and look at it frame by frame with
LEFT ARROW and RIGHT ARROW. If you see frames where the feet seem to push through the floor, adjust
the height of the pelvis accordingly and set "Loc" key frames, or adjust the rotation of the bones in the
offending leg and set "Rot" key frames for them (Figure [c-bad]).
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Game Character Animation using Armatures
Game Logic
□
Figure [c-bad]. Bad positions of the character's legs
If you prefer working with Ipo Windows, you can edit action channel Ipos directly, though this is not always
required. To do this, select an action channel in the Action Window, switch one window into an Ipo Window
with SHIFT-F6 and choose "Pose" from the Ipo-type menu.
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• Note that Action Ipos display rotations in quaternions instead of Euler angles. This gives nice
predictable results when working with complex combinations of rotations, but can be a bit unusual to
work with. The best tactic is to set the action value of the quaternions by inserting "Rot" key frames in
pose mode, and only using the Ipo Window to adjust the way the curves are interpolated.
• To view several different Ipos in different windows, you can use the "pin" icon in the Ipo Window
Header buttons to prevent the displayed Ipo from changing when you change object selection.
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□
Game Logic
When adding game logic to your character, make sure to put the game logic on the object which can use the
actuator you want. For example, "Action" actuators on the armature object itself, rather than on the mesh.
Similarly, "ShapeAction" actuators on the mesh object.
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Game Character Animation using Armatures
Game Logic
□
Figure [c-dyn] . Dynamic object for the character
If you are making your character a dynamic physics object, you may need to adjust the center point of the
armature based on the size of the dynamic object to make sure that the character's feet touch the floor. The
character's feet should touch the bottom of the dotted dynamic object bounds (Figure [c-dyn]).
Generally speaking, you will need to add an Action Actuator for each different action that your character can
perform. For each actuator, you will need to set the start and end frames of the animation, as well as the name
of the action.
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Blender has the ability to create smooth transitions or to blend between different game actions. This makes the
motion of game characters appear much more natural and avoids motion "popping". To access this
functionality, all you have to do is adjust the "Blending" parameter in the Action actuator. This field specifies
how long it will take to blend from the previous action to the current one and is measured in animation
frames. A value of "0" indicates that no blending should occur. Note that this blending effect is only visible in
the game engine when the game is run.
Action actuators have many of the same playback modes as Ipo actuators, including looping, playing, flippers
and property- driven playback.
You should try and design your game logic so that only one action is triggered at a time. When multiple
actions are active at the same time, the game engine can only displays one of them on any given frame. To
help resolve ambiguity, you can use the "Priority" field in the action actuator. Actions with lower numbers
will override actions with higher numbers.
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Game Character Animation using Armatures Game Logic
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Flying Buddha Memory Game
"Flying Buddha" is a game designed by Freid Lachnowicz (artwork, models, textures) and me (Carsten
Wartmann, Python and game logic). The goal of the game is to find pairs of gongs, like in the good old
"Memory" game.
Besides that, it also includes some action elements, like the dragonfly which will become angry (note the
indicator on the top-right) if you jump too high. Also it requires some good timing for the controls of the
Buddha. The Buddha's goal, reaching "Zen" is completed when he has found all pairs. For competitions the
time needed to solve will be displayed on screen.
Flying Buddha game controls
Controls
Description
CURSOR KEYS
Movement, you can steer in the air and slow down your fall
SKEY
Select a gong
Load the game Games /FlyingBuddha .blend from the DVD and have fun playing it!
Accessing game objects
Accessing individual objects from Blenders game engine is not trivial. In the "Flying Buddha" game, I needed
a possibility of randomly shuffling the gongs at game start.
Generally speaking, it is a good thing to have as much game logic as possible contained on the object that
needs that logic. This helps when re-using this object in the same or even different (Blender) scenes. So my
first idea was to let the gongs choose a new position themselves. But this soon turned out to be too
complicated, because of synchronizing problems and complex logic in the gongs.
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Accessing game objects
I then decided to use an object to control the shuffling process, and have the information about the other
objects including their positions is gathered by a Near Sensor. This approach has many advantages. For
example we can filter out whole groups of objects with the "Property:" field, we are not bound to a fixed
number of objects etc.
LogicBricks
Load the file Tutorials/FlyingBuddha/FlyingBuddha_simple .blend from the DVD. It
contains a simpler version of the "Flying Buddha" game, which does not contain all the intro scenes but is
fully functional (press CTRL-LEFT for a full screen view). Use this file to explore the Game Logic.
The difference in the full game and this tutorial file are build-in debugging and testing logic. Most notably is
that you can test the re-shuffling of the gongs every time by pressing SPACE. The logic for this is on the
"Flamethrower" object (on layer 4).
Have a look at Figure [fb-lbs] the interesting parts in this context are the Sensors "mixitbaby" and "near".
Both are connected to a Python Controller, which is then connected to a Message Actuator. Also note the
"shuffle" Property, this controls the number of swapped pairs. The other Bricks are not related to the
shuffling, they are needed for other game parts.
□
Figure [fb-lbs]. LogicBricks for shuffling the gongs
As you can see, the Near Sensor only looks for objects carrying a Property with the name "num". Also make
sure that the "Dist:" setting is high enough for the Near Sensor to cover all objects.
The Python Controller will be called every frame by the Property Sensor as long the Property "num" is in the
range from 1 to 1000.
Shuffle Python script
Open a Text Window (SHIFT-F1 1) and choose the script "Shuffle.py" with the Menu Button.
# Shuffle script, swaps positions of two gongs
import GameLogic
def ranint (min, max) :
return (int (GameLogic . getRandomFloat ( ) * (max+1-min) +min) )
contr = GameLogic . getCurrentController ( )
owner = contr . getOwner ( )
key = contr . getSensor ( "mixitbaby" )
near = contr . getSensor ( "near " )
mess = contr . getActuator (" shuffled" )
# collects all gongs
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objs=near.getHitObjectList ()
if key . isTriggered ( ) and len (ob js) ==20 :
owner. shuffle = owner . shuffle - 1
if owner . shuffle< ; :
GameLogaddActiveActuator (mess, 1)
else :
gl = ranifiDt 19)
g2 = rani(i0tl9)
Shuffle Python script
posl = oifgpi ] . getPosition
pos2 = okfgfS ]. getPosition
obgjsl ] . setPosition (pos2 )
obgjS ] . setPosition (posl )
Listing [fb-py]. Script to shuffle the gongs
So lets have a look into the script. The lines 1 to 12 contain the usual initialization, and getting information
about the Controller, Sensors, Actuators and the owner which is needed to access Properties. The definition of
a new function in line 5 is used to make a random function which returns an integer number in a specified
range. This will save us much typing later.
In line 15 the first important step is done, using the method getHitOb jectList ( ) of the "near" object,
we collect all game objects within the Near Sensors range into the list "objs".
Line 17 tests if the Property Sensor ("key") is triggered and if all objects (the gongs) are collected in the
"objs" list. This is necessary to avoid Python script errors due to uninitialized objects.
In line 18 we decrement the Property "shuffle" by one to keep track how many swaps we already did.
The i f -block beginning in line 19 executes the Message Sensor connected to the Python Controller if the
Property "shuffle" is less then zero, the message can then be used to start the game.
The else-block is executed when "owner.shuffle" is bigger than zero. This means that gongs need to be
swapped.
In lines 22-23 we get two random numbers into the variables "gl" and "g2". The numbers will be in a range
from to 19 because we have 4x5=20 gongs, "gl" and "g2" are the indices of the gongs we want to swap in
the next lines. Note that lists in python start with the element "0".
In the lines 25-26 the script reads the positions of the gong-objects using the random indices. The method
used here is getPosition ( ) . You can insert a print posl, pos2 statement after line 26 to actually see
the gong positions while running the game.
Python is an auto documenting language. Use a print dir ( ob ject ) statement to find out what methods
an object provides.
The final two lines then swap the positions of the two gongs. The first object indexed as ob j s [ gl ] is set to
"pos2" which is the position of the first gong. Same for the other gong. You can see the shuffling process in
the game itself by looking at the gongs from the backside.
In this tutorial I showed you how to use Python in the game engine to access and change objects in a scene.
We used this approach to keep the game logic local on the objects. If you are used to non object-oriented
programming languages or systems, this may appear strange to you at first. But this approach has many
advantages. For example, you don't need to change the logic while editing your scenes or adding objects, the
script will even work when adding objects while running the game. Also, re-using the logic in other scenes is
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much easier this way.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Apricot OpenGame Project: Yo Frankie!
'" fHi rtft
\
□
After Orange and Peach, Blender Institute did continue with a new open project: Apricot. This time it wasn't a
movie but a 3D game! Starting February 1st 2008, a small team of again the best 3D artist and developers
developed a game jointly with the on-line community. The main characters in the game are based on the short
3D animation open movie Peach.
Just like our previous Open Projects Orange and Peach, the game itself and all of the production files will be
published under the Creative Commons, free to be reused and for everyone to learn from. More importantly,
the team was challenging Blender and Crystal Space to the max, inspiring the entire development community
to prove an open source production pipeline is ready for industry quality 3D game creation. .
Now the project is over and lead to even to two games! It was planned to use the crystal space game engine,
but during the project also the Blender game engine was used to make a own game. This massive use of
Blender for creating realtime content lead to a huge leap in Blender development, especially in the realtime
part, just as the open movies "Elephants Dream" and "Big Buck Bunny" did.
In this book we will of course concentrate on the Blender game engine and just touch the surface of the game,
on the the "Yo Frankie!" DVD you will find:
• A full functional prototype in the Blender Game Engine, running in Linux, Windows and OS X.
• A complete level in Crystal Space, with installer, running in Linux, Windows and OS X.
• All .blend files, models, textures, sound clips, game sources, and so on... all the material used to
create the game.
• Documentation and video tutorials by the team members about all technical aspects the game; like
how to re-use assets, animate characters, or add new levels.
• The Big Buck Bunny movie in various formats
Visit the apricot.blender.org blog for more information about this project.
Creative Commons
.creative
fcc 'commons
□
The Apricot open game project, the data weall publish online and on the DVDs, and all of the contents on
this website is licensed under the Creative Commons Attribution license 3.0. If any content on this site is not
licensed as such, it will be clearly indicated. In short, this means you can freely reuse and distribute this
content, also commercially, for as long you provide a proper attribution.
The attribution is: (c) copyright Blender Foundation - apricot.blender.org. Excluded from the Creative
Commons is: all logos (including Blender logo, Apricot logo, Yo Frankie! logo, Creative Commons logo) and
associated trademarks.
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Apricot OpenGame Project: Yo Frankie^o Frankie! Blender Game Engine Logic By Campbell Barton
Yo Frankie! Blender Game Engine Logic By Campbell Barton
□
The game is separated into a number of blendfiles. characters, levels and props. The levels and props have
almost no logic, only properties assigned to them that the characters use to define how to interact with them.
The levels contain mostly static scenery, linking in characters, props and effects as groups.
Having a character with its camera, animations, sounds and logic in an external blend file is extremely
powerful, not only being able to link the one character into multiple levels, but also have multiple instances of
that character in a level.
Logic Sharing
Once we had the logic for the sheep, we wanted to be able to add extra characters without having to redo the
logic. This was made possible by the recent addition of group instances in the game engine, added especially
for the Apricot project.
T
□
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Apricot OpenGame Project: Yo Frankie! Logic Sharing
imMsMwd character groups
Character specific objects such as the armature, mesh and shadow mesh of each character are parented to a
dummy mesh that runs the logic. All three groups share the logic objects but have unique armature and
meshes.
To avoid each character behaving in the same way, a script runs when the character starts that sets a "type"
property based on the children. The type property determines if the character can attack, get kicked, carried
and how aggressive they are.
There are two playable characters (Frankie and Momo) which also share logic but have their own unique
mesh and armature.
No changes in behavior are needed however they do need to use different key layouts and have their own
section of the screen (splitscreen). As with the sheep this is done on when the character starts, for the moment
only one or two players are supported at once, but adding more would be trivial.
States
States are a new addition to blender added for the Apricot project, allowing us to group logic into states that
can each be enabled and disabled (you could think of them as logic layers). States were used heavily with all
complex gamelogic. Frankie for example has states such as idle, walking, running, falling, gliding, hanging,
drowning and death. Each state has a number of sensor and actuators that will switch states under certain
conditions.
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Apricot OpenGame Project: Yo Frankie!
States
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Here is an example of how states switch during gameplay
• Initial State -> Falling
• Ground Collision -> Idle State
• UpKey -> Walk State
• No Ground Collision -> Fall State
• Water Collision -> Drown State
Logic Elements
Frankies Camera
□
This file (Blends/YoFrankie/tutorialf iles/bge_camera_example .blend) shows how the
apricot camera works. Although a 3rd person camera facing forward is not overly complex there are are still
various issues to overcome.
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Apricot OpenGame Project: Yo Frankie! Logic Elements
The initial problem we had with blenders camera was that Frankie could become obscured by objects which
made the game unplayable.
We started by parenting a camera to Frankie, using blenders slow parent feature to dampen the cameras
response to Frankie, avoiding jitter and jarring motion. To prevent trees and walls getting in the way of the
camera, a ray sensor from Frankie points towards the camera and uses a python script to scale the camera
parent based on the collision location.
Notes:
• There is a dummy character in this file to test movement, added so the camera has something to look
at.
• The scene with the terrain and pillars is a 'Set Scene' called "example_scene".
• Keys for movement are Arrow Keys and Space for jump. Keys 1 and 2 set orbit on and off.
Objects and their use (matching frankie. blend)
• Frankie - Parent mesh with all player control and properties
• FrankieDummy - Mesh that shows Frankie, is a rig and mesh in frankie.blend
• Camera_Ray - An empty that tracks the camera from Frankie's position. This casts a ray to the camera
and detects if anything is in the way of the view.
• Camera_Scaler - This is a parent to the camera so scaling it changes the camera distance from
Frankie. The scale is controlled by a python script that uses the Camera_Ray hit position to set the
scale, (this is the only script used by this camera setup). There is also an orbit mode that makes this
object rotate about to see Frankie better from all sides while he is idle, drowning or dead.
• SlowVertParent - This is the parent of the camera, slow parent is used so changes in scale or Frankie
turning are not applied instantly to the camera. We needed to use a vertex parent for the camera
otherwise the camera would have scale applied to it which caused distotion of the 3D view.
• MainCam - The main camera tracks to the Camera_Ray
Frankie's States (Simplified)
□
This character logic example
(Blends /YoFrankie /tut or ialf iles/bge_logic_s tat e_example .blend) is based on
Frankie's logic and shows how you can use states to control behavior without setting any properties or running
python scripts.
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Apricot OpenGame Project: Yo Frankie! Logic Elements
Python should be used to add more advanced functionality, but using states helps give scripts a limited
context keeping them smaller.
Keys
• Up, Left, Right - Movement
• Space - Jump
Level Properties
• ground - use to detect floor you can walk on
• kill - sends you to the death state
States
1 Idle state. Can jump, walk and turn from here
2 Walk state. Can jump, idle and turn from here
3 Jump State. Only ever enabled for one logic tick, adds upward force and goes into fall state immediately.
This is because motion from other states (walk in this case) can interfere with the jump force.
4 Fall State. Can land from here. This state is enabled on startup (notice the black dot over the state) and is
enabled whenever Frankie is not touching a 'ground' property object.
6 General State for turning, and checking if Frankie touches any 'kill' objects. This state is always enabled
while Frankie is alive, having one of these states is useful for situations you want the character react to
regardless of his current behavior.
15 Death, this state turns off the general state, removing user input, waits for 4 seconds and ends the object.
Level Portals
Your in file
"pomLtesO-blend"
□
This collection of blendfiles (Blends/YoFrankie/tutorialf iles/portal_test .blend) show
how a single character can be linked into any number of scenes and blendfiles, easily moving between them
with portals.
The character is a group of objects with game logic and a camera. This group is then linked into many levels
keeping the character logic in one place where it can be edited.
These examples focus on how we did portals, which can do the following.
• move to another location in the level.
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• move to another scene in the blend file (object if its defined)
• move to another blend file (scene and object if they are defined)
• keep the properties of the character such as life and inventory between between scenes and blendfiles.
To make a portal just add an object you can collide with and give it the property "portal", value
"SomeObjectName" for eg. On touching the portal you'll be transported to an object called
"SomeObjectName".
If you want to move to another scene add the property "portal_scene", value "MyOtherScene" for eg.
To go into another blend file add the property "portal_blend", value / /level_2 .blend for eg. The value
is a path to another blend file, the / / prefix means its in the same directory as the current blend file.
When using "portal_scene" or "portal_blend" properties, the "portal" property must be present, if you don't
want to set an object location, its value should be an empty string.
The properties described work the same way as the apricot levels, however character scripts were modified for
the purpose of this example.
Take a look at the portals in this directory for examples.
Splashing
□
Here is an example (Blends /YoF rankle /tut or ialf lies /bge_splash_example .blend)
showing how splashes are created for the water and lava levels.
Water objects need collision sensors linking to "splash_logic'"s controller. In this case there are two water
objects, but there is no limit.
splash_logic runs a python script called "detect_splash" whenever there are collisions, The "detect_splash"
script moves "splash_logic" to each collision location and adds a splash object.
This way many splashes can happen at once.
It is up to the objects that land on the water to float, sink or be removed, they only need to collide with the
water. In this example the cube's dynamics are suspended and it is removed after 200 logic ticks.
The empty objects above are there to create objects that make a splash however any object could be dropped.
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The splash object its self must be in a disabled layer for the AddObject actuator to work. See layer 20.
2 Player Split Screen
□
This file (Blends/YoFrankie/tutorialf iles/bge_splash_example .blend) shows how two
instances of the same character group can have their own keys and screen assigned on started.
This is done by having a python init script for each character that assigns a unique ID, used to configure each
differently.
Once the script runs, the state is changed to respond to user input only. The character objects in this scene are
dupligroup instances. Change to the "character_group" scene to see their logic and see the
"frank_init_2player" script to see how they are initialized.
Use the arrow keys for player one, WASD keys for player two.
Menu
Options
• radio I
Toggle 1
(Toggle [
* j"adio 2
• I radio 3
Save Config
Load Config
back 1
□
This blendfile (Blends/YoFrankie/tutorialf lies /bge_menu_example .blend) shows a
simplified version of the YoFrankie start menu.
The menu has the following functionality:
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• input from mouse, keyboard or joystick
• menu items can load scenes, blenderfiles or trigger your own actuators.
• toggle and radio menu items can be used to set configuration options.
• options can be saved an loaded to a file using new functionality in the game actuator.
• logic is generic, reusable between multiple menus.
Implementation
The basis of the menu is quite simple, all objects starting with "item_" are alphabetically sorted and treated as
menu items. Only one item can be active at a time by pressing up/down or passing the mouse over it. Pressing
enter or clicking will execute the menu items action.
The "menu_select" script is where most of the menu logic is controlled. It runs on the "menu_logic" object,
reacting to user input by scanning the scene for "item_" prefixed objects and adjusting their properties
accordingly.
The "active" property is used by all items. When set to 1, the items sensor detects this and plays an animation.
For YoFrankie we chose to use invisible items so we could attach animations to one or more objects, giving
us a larger area for the mouse to activate as well.
Item Activation Type: Trigger
These items only need an extra "trigger" property. When the menu item is activated trigger is set to 1. The
items own logic needs to check for the trigger value to act on it. Once executed the trigger value needs to be
set back to zero. See the menu items "Quit", "Save Config" and "Load Config"
Item Activation Type: Portal
Using the same properties as in the levels, portals can load blendfiles, scenes and objects (to set the initial
location).
The properties are
• active: described above.
• portal: object name
• portal_scene: scene name
• portal_blend: blendfile name
See the menu items "Open Blendfile", "Configure" and "Back" for examples of a portal.
Configuration
If you want to configure settings in a menu, you can use the python dictionary "GameLogic.globalDict" which
is kept between loading files and can be saved and loaded to a file with the game actuator.
All game configuration is kept in a dictionary - GameLogic.globalDict['conf ].
There are currently two types of buttons that will automatically adjust the python dictionary when activated.
Both use the "conf_key" property to specify which setting is changed.
Even through there are only a few buttons, many configuration buttons can be added without making any
changes to the menus inner workings.
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See the "init_options" script and menu items in the options scene to see how they work.
Toggle
This is fairly simple, the toggle button switches value in the configuration dictionary on and off.
• active: described above.
• toggle: or 1, the menu item checks this to display a larger dot when enabled.
• confjsey: toggle this option, GameLogic.globalDict['conf ][conf_key] = True or False
Radio
Unlike the toggle button, multiple radio buttons share the same conf_key.
• active: described above.
• radio: the value of confjcey when the button is enabled. So for instance 3 buttons low/med/high
would have "radio" values of 0,1,2.
• enabled: only 1 of the radio buttons sharing the same confjcey will ever be enabled at a time. This is
used to play an animation making the enabled option stand out.
• conf_key: toggle this option, GameLogic.globalDict['conf ][conf_key] will be set to the "radio" value
of the button thats enabled.
This example omits key binding configuration since it is fairly complicated and specific to YoFrankie.
Frankies Logic
Frankie's behavior is made from a number of objects with an invisible parent that does almost all the logic.
The logic bricks are divided into manageable states (walk, run, fall, idle etc) so each state can be edited
without dealing with the logic from other states.
There are two main exceptions to this rule, status (15) action (16) so Frankie can execute actions and his life is
maintained throughout gameplay.
Sensor logic bricks detect...
• user input (keyboard or joystick)
• collisions with special level elements (eg. lava, water, bounce, portal).
• property changes to health and inventory.
Actuators are used to...
• play animations and sounds
• enter new states
• set properties for health, carrying and timers.
• apply physics forces (eg. jumping and running)
• constrain orientation (eg. walk - upright, run - ground parallel, glide - limit pitch).
Scripts are needed for advanced functionality like...
• gliding, where Frankie's pitch influences speed and decent.
• hanging off a ledge, where rays are cast to detect the top of the ledge setting Frankie's vertical
position.
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Frankies Logic
• Context sensitive actions that test surroundings for enemies, what Frankie's carrying and his
inventory.
Frankie's States
□
• idle (1) state is the default state when Frankie is on the ground and not doing anything.
• walk (2) when holding forward or backwards.
♦ servo motion actuator to maintain constant speed.
• run (3) when holding down action key and forward.
♦ linear velocity only is used to move Frankie forward.
♦ a distance constraint actuator with the rotation option enabled is used to keep Frankie running
parallel to the surface of the ground (making loop-the-loops possible)
♦ run speed is controlled from a the "frank_run_speed" script, that adjusts the run speed based
on the "boosted" property and Frankie's pitch (to accelerate around a loop-the-loop).
• fall (4) state is set when Frankie is not colliding with any ground objects and immediately after
jumping.
♦ Frankie is constrained to being upright while falling using orientation constraint actuator.
♦ From this state Frankie can also bounce or change states by landing on another player to be
carried, grab onto a ledge or glide by holding down jump.
• ledge hang (5) state continuously keeps Frankie attached to an edge where Frankie can shimmy from
side to side, drop off or climb if there is ground above the ledge.
♦ This is one of the few states where actions are disabled (state 16)
♦ dynamics are not suspended, the python script keeps Frankie attached to the edge.
• carried (6) when Frankie's "carried" property is non-zero, this state is set, almost all functionality is
disabled and Frankie can only throw objects.
• idle animation (8) when idle for a while this state is added, using "frank_random_anim" script to play
a random animation actuator.
♦ This state differs from others because it's added on top of another state. Since this state only
plays an animation it doesn't matter if it's disabled by another state being set, such as walking
or falling.
• death (1 1) is set when Frankie's life is zero, this state will immediately switch to state 12 or 27 if there
is lava collision.
• death ground (12) plays the death animation then sets respawn state 26. This state is set exclusively,
disabling all player input.
• stats (15) updates Frankie's health, reacts to being hit, touching water, collects pickups, activates
portals and sends messages to the heads up display (HUD) overlay scene.
♦ This state will run most of the time, in all other states where Frankie has free movement - (not
death, drown or respawn).
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• actions (16) state detects input and performs actions - a combination of playing animations and
performing action logic. The logic for catching and checking if Frankie is on the ground or not is also
done in this state.
♦ the "frank_action_all" script senses key input, checks what there is to kick or throw then sets
the "action_name" property and plays the animation. This keeps the script running while
"action_name" is set. Running the logic on keypress would be simple but not very
convincing, so the script has a frame set for each action to execute logic, after the frame in the
armature animation and the "action_done" property is set.
♦ You can add your own actions by adding a key sensor, action actuator and following the
conventions in "frank_action_all" script.
♦ this state also runs along side most other states (as with state 15), however it's disabled during
ledge grab and ledge climb.
• jump init (18) state plays a sound, sets the linear velocity and resets the "jump_timer" and "grounded"
property.
♦ After setting the properties we immediately switch to the fall state. This is done because
having all jump actuators attached to controllers in idle, walk and run states would be hard to
maintain.
• glide (19) state is enabled by holding jump while falling. All of the glide logic is performed in the
"frank_glide" script which deals with the dynamics of speed and pitch to enable swooping and
remaining airborne for a short time.
• ledge climb (20) is used when pressing forward while hanging on a ledge. An animation plays while
Frankie moves up onto the ledge above.
♦ Servo motion actuators move Frankie up and forward at a fixed speed without having to
suspend dynamics.
♦ The motion actuators are synchronized with the animation using delay sensors to time the
change in motion from upward to forward.
• stop idle animation (23) resets the idle animation timer and disables camera orbit, then disables the
animation state and its own state.
• respawn (26) resets Frankie's location and restores almost all his properties to their original values.
• death lava (27) is the same as death ground, except a different animation and sound play.
• drown (28) state is similar to the death states, except instead of respawning, the "frank_drown_revive"
script moves Frankie to the second last location where he was touching the ground.
Frankie's Properties
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Frankies Logic
Int
Narneid
-1
D
Int
Narne:grounded
D
Bool
Name:predator False
D
Bool
Name:kickable False
D
Int
NarneM
D
String
Name:orig_pos
D
String
Narne:ground_pos
D
String
arne:ground_pos_old
D
Timer
rn e :wate r_to u c h_ti m e
1.000
D
Int
Narne:carnera_orrjit
D
Timer
ame:idle_anirn_timer
-S.000
D
Int
Narne:carrying
D
Int
Narne:carried
D
Timer
Name:force_walk
0.000
D
String
Name:action_name
D
Int
Name:action_done
D
String
Name:throw_item
D
Int
Narne:life
13
D
Int
Narne:life_max
13
D
Timer
Narne:revive_tirne
1.000
D
Timer
Narne:jump_time
0.000
D
Int
Narne:double_jurnp
2
D
Float
Narne:glide_2_init
0.000
D
Timer
Narne:wall_run_timer
1000.000
D
Timer
Name:boosted
0.000
D
Int
Name:can_climb
D
Timer
e:ledge_regrip_timer
100.000
D
□
• id This is a unique player ID integer for each player, or 1 for players 1 and 2. This is used when
initializing the player to set key keyboard preferences and splitscreen. When you throw an object,
your "id" is assigned to its "projectile_id" so we know who last threw the object. Starting as -1,
correctly initialized in the script "frank_init"
• grounded is used by a lot of Frankie's logic bricks and scripts to know if he is on the ground or not.
This value is managed by the "frank_ground_test" script (State 16) where a "ground" collision and -Z
ray sensor are used to detect if the ground state changes. This property could be removed and be
replaced with ground collision sensors everywhere, however a collision sensor alone can jitter on
bumpy terrain, the combination of ground + ray gives better results.
• predator is used by sheep, ram and rat logic to tell you're an enemy and to attack or run away from
you.
• kickable is used for 2 player mode to allow you to kick each other. Sheep and rats also have this
property.
• hit is set by other objects logic when you're attacked (rats, rams or a second player) When this is set,
Frankie's life property will have the hit value subtracted and the hit value set back to zero. The
"frank_health" script responds to non-zero hit values. Using this method makes adding in your own
enemies easier, all they need to do is set the "hit" value of the object they are attacking.
• orig_pos stores Frankie's initial location when entering the level. When Frankie dies this position is
used for respawning. This value is initialized in the "frank_init" script. It is used in "frank_respawn"
and as a fallback location in "frank_revive" scripts.
• ground_pos and ground_pos_old properties are updated every second, storing the last instance
Frankie was on the ground. At the moment this is only used for reviving after drowning, where
Frankie is revived at the (2nd) last point where he touched the ground. ground_pos_old is always a
second older then ground_pos to make sure the ground location used isn't too close to the water and
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Apricot OpenGame Project: Yo Frankie! Frankies Logic
set immediately before drowning. These values are set in frank_ground_pos
• water_touch_time Simply drowning when Frankie touches the water doesn't work well, especially
jumping off drowning sheep. This timer is used to make sure Frankie is touching the water for a short
period before switching to the drowning state, (see water_timer sensors and controller in State 15)
• camera_orbit is an integer used to set the camera orbiting around Frankie when he plays idle
animations, drowns or falls in lava. The "Camera_Scaler" object has a sensor that checks this
property, running a motion actuator when its nonzero and plays an ipo when its false to set the
rotation back. See "Camera_scalers" orbit_on and orbit_off controllers.
• idle_anim_trigger This timer is used to play idle animations when Frankie has been inactive for a
while. It is initialized to a negative number and will orbit the camera, then add the idle animation state
around 0.0 See logic bricks in State 1 with the idle_anim prefix
• carrying integer is set to 1 when Frankie is carrying something. Many scripts use this to check if
Frankie can do actions like collect items, tailwhip, double jump and run. The main logic setting this
value is the "frank_carry" script which runs whenever an object with the "carried" property touches
Frankie. See State 16 frank_carry controller.
• carried defines this as an object that can be carried (player 1 can carry player 2 for example). Its value
is used by scripts and logic bricks to know if you are being carried. When this is nonzero state 6 is set
where dynamics are suspended and Frankie can't do very much (except throw anything he's already
carrying).
• force_walk timer is used when we want to stop Frankie from running, when the timer is below zero
the run state will switch immediately back to walk. This is set to always be negative when carrying an
object, and used to force walking for a short time when Frankie is hit, throwing, kicking and
tail-whipping.
• action_name is used when Frankie performs an action - currently its value will be either
"throw_carry", "throw", "kick" or "tailwhip". This means we know what action is currently running
and also stops multiple actions from running at once. Once finished the value will be set to an empty
string. See state 16 where the "frank_action_all" script is used to control all the actions
• action_done is used by the "frank_action_all" script to check if the function associated with an action
has run yet. Without this, actions could not take place in the middle of an animation. See state 16 also
• throw_item stores the item Frankie will throw next. If there were more collectible items that had
different purposes, this could be used to cycle through active items. See "frank_sense_pickup" script
in state 15 where the last collected item sets the "throw_item" and "frank_action_all" in State 16
where the "throw_item" defines the item to throw next
• life for storing Frankie's current health and for updating the HUD meter. See the "frank_health" script
in State 15
• life_max Frankie's maximum health value to limit how much life Frankie can pick up. See
"frankie_sene_pickup" in State 15
• revive_time is set to zero when Frankie is hit, another hit wont be applied until "revive_time" is over
1.0 See "frank_health" script from state 15
• jump_time timer is set to 0.0 upon jumping, where it is used to ignore any ground collisions for a
short time and then to detect if it's too late to do a double jump, jump time is also re-used for timing
the glide duration. See "frank_ground_test" on State 16 and State 18 where the jump values are set
• doublejump is used to check if Frankie has double-jumped (since you can only double-jump once)
See "frank_fall" script in State 4.
• glide_z_init is set to Frankie's Z axis when he starts gliding, its used to make sure he can never glide
to a higher level then when he starts. See the "frank_glide" script in State 19
• run_wall_timer is used so Frankie can flip off a wall when he runs into any wall with the "slip"
property. See "frank_wall_run" script in State 3
• boosted is set set when Frankie catches a butterfly (touches a pickup with a "boost" property), making
his colour flash run a lot faster. See "frank_run_speed" script in State 3, "frank_sense_pickup" where
the boost value is set
• can_climb is set when hanging by casting a ray above the ledge to detect if there is any ground for
Frankie to climb onto. If this is not zero, pressing up while hanging will make Frankie climb up onto
the ledge. See "frank_ledge_hang" script in State 5
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Apricot OpenGame Project: Yo Frankie! Building a simple test level
• ledge_regrip_timer is used when dropping from a ledge (down key while hanging) to stop Frankie
from grabbing the ledge immediately after dropping. See the "frank_ledge_collide" script in State 4
Building a simple test level
Most of the game on the DVD uses Blenders GLSL materials, so it is needed to use a decent graphics card to
get the full look and performance. On the "Yo Frankie! DVD" there is also a (graphically) simple game.
Level Design Physics/Logic
Setting up a level to run with Frankies logic is easy to start with, just make sure any area you want to stand on
has the "ground" property.
From here you can play the level, you'll probably notice glitches but these can be dealt with by fine tuning the
level, (see notes below).
Physics Objects
The current method of defining ground and barriers is limited in that it requires you to have separate objects
for each.
For the Yo-Frankie levels it was easier to remove collisions from the scenery and add invisible physics
objects.
Physics can be disabled for scenery in the game logic buttons. Physics only objects can have their render
option turned off in the outliner so they are initialized invisible (saves adding UV's and using the invisible
option).
Materials
Walls and other vertical surfaces you dont want to run up should have a material with no friction (See the
materials DYN button).
Properties
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Apricot OpenGame Project: Yo Frankie!
Properties
□
These properties are checked for in Frankie and other entities logic, so the characters interact correctly with
the level.
• ground property is used to define anything Frankie can stand on. These surfaces don't have to be flat
(a loop-the-loop for instance has the "ground" property). However make sure this isn't assigned to
walls and barriers.
Platforms you jump up onto should be surrounded by a barrier that doesn't have the "ground" property, The
top should be outset about 0.05 so collision with the top of the barrier won't also collide with the ground,
otherwise Frankie will start walking before he is on top of the platform.
• slip wall property makes back-flips off walls possible when run directly into. Running at the wall
from an angle will cause Frankie to run parallel to the wall. This isn't necessary for gameplay to work
but makes running around a level feel smoother. The value of this property isn't used.
• ledge property is used to define areas that Frankie can hang. on. The value of this property isn't used, o
These should be vertical strips 0.45 deep, o Ghost collision option can be used if you want to be able
to ungrip and fall through the ledge-grab geometry (with branches for example).
• bounce property will make the object bounce Frankie back up in the air when he falls onto it. The
value of this property isn't used.
• kill property will make Frankie lose as many lives as the kill value which must be an integer.
• water property should be applied to the surface of a river so Frankie drowns when touching it for a
short time.
This object should be a ghost. The value of this property isn't used.
• lava similar to water, just plays a different animation for Frankie.
• liquid this property should be applied to water or lava objects so pickups will disappear when
touching them. The value of this property isn't used.
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Apricot OpenGame Project: Yo Frankie! Starting A New Level Using Linked Groups
Starting A New Level Using Linked Groups
This tutorial will take you through linking groups from external blendfiles, into your own scene, using the "Yo
Frankie!" characters and other assets for your own level.
Set Blender to the default scene. Now scale the Cube down to a flat ground and make it also bigger. Change to
the Logic Buttons F4 and add a Property "ground" to our ground cube. This will tell the player characters
(Frankie, Momo, the sheeps etc.) where to walk on.
Now use the menu "File->Append or Link" or SHIFT-F1 and browse to the DVD, look for the folder and file
Blends /YoF rankle /chars/ frankie .blend. Click it with LMB and you will enter the file itself.
Here you can browse all elements in that file. Now click on "Group" you will see some groups, containing
Frankie the main character and also Momo.
g :\Ble ride r\Ap ricoftcharsVfrankre .tile nd\G roup\
T) | FlyingSq
uirrel
Load Library
,
Cancel
Flying Squirrel
FrankyNo Logic
MomoMonkey
MomoNoLogic
{Wl 151 hSil-*H I man unary
| Relative Path? [ Appsrm
□
Look at the header, right now the "Append" button is active. This will append the group into our scene. We
should use this option when we want to change the imported object or character later. However, it is better to
copy the needed things from the original location into a own location and use the power of library linking.
Now activate "Link", for this quick test we will just use the characters as they are supposed to be used in the
"Yo Frankie!" game. So select "FlyingSquirrel" with LMB and use the "Load Library" button.
Remember that when you use "Linking" you always have to put the DVD into the drive when you try to load
your new level. For starting a real new game or a level which will integrate into the game you should copy the
DVD contents to a place on your harddisk.
□
Right now nothing appeared in our scene, no wonder, we linked a group. Place the 3D Cursor where you want
to add the character and use the Toolbox with SPACE->Add->Group->frankie->FlyingSquirrel to add a
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Apricot OpenGame Project: Yo Frankie!
dupligroup instance..
Starting A New Level Using Linked Groups
□
You should now be able to run the game by pressing PKEY, however the scene will be without textures. So
stop the game engine with ESC and choose "Blender GLSL Materials" from the "Game"-menu and switch to
the textured viewmode by pressing ALT-Z.
You should now also see a shadow on the ground, if not you need to assign a material to the ground. It is best
to keep the main characters on layer 1 and also put there the ground and all elements on which the characters
shadow should fall.
You already noticed that the screen splits into two views, even if there is no second player. This is because we
need some initialization for the main characters. Split the big 3D view and change one window to a Text
Editor using SHIFT-F11. Now use ALT-0 to open the script
"B lends /YoFrankie/ in it_opt ions .py".
Setup default configuration options
use GameLogic . globalDict which is stored between loading blend files
i i i
import GameKeys
def main ( )
try: conf = GameLggabalDict [' CONFIG ' ]
except: conf = GameLogiglobalDict [' CONFIG '
def confdef (opt, value) :
if opt not in conf:
[opt] =cOTafLue
{}
confdef
confdef
confdef
# Keys
# PI
confdef
confdef
confdef
( 'PLAYER_COUNT' , 1)
( 'GRAPHICS_DETAIL' , 2) # 2 == high
( 'GRAPHICS_GLSL' , 1) # toggle
( 'KEY_UP_P1 ' , GameKeys. UP ARROWKEY)
( ' KEY_D0WN_P1 ' , GameKeys . DOWNARROWKEY)
( 'KEY_LEFT_P1 ' , GameKeys . LEFTARROWKEY)
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Apricot OpenGame Project: Yo Frankie!
Modify Apricot Files
confdef
# P2
confdef
confdef
confdef
confdef
# PI
confdef
confdef
confdef
# P2
confdef
confdef
confdef
( 'KEY_RIGHT_P1 ' , GameKeys . RIGHTARROWKEY)
( ' KEY_UP_P2 ' , GameKeys . WKEY)
( 'KEY_D0WN_P2 ' , GameKeys. SKEY)
( 'KEY_LEFT_P2 ' , GameKeys . AKEY)
( 'KEY_RIGHT_P2 ' , GameKeys . DKEY)
( ' KEY_ JUMP_P 1 ' , GameKeys. MKEY)
( 'KEY_THR0W_P1 ' , GameKeys . SPACEKEY)
( 'KEY_ACTI0N_P1 ' , GameKeys . NKEY)
( ' KEY_JUMP_P2 ' , GameKeys . GKEY)
( ' KEY_THR0W_P2 ' , GameKeys . JKEY)
( 'KEY_ACTI0N_P2 ' , GameKeys . HKEY)
import Rasterizer
Rasterizer. showMouse (True)
main ( )
Init the main characters
Now add an Empty and use a Always Sensor to just call this script one time. To do so you need to switch of
the pulse button.
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□
We can now add more elements. First try to add some water, for now it is not important to make good looking
water, so we can just add a plane and give it a blueish color. Give it a Property "water" and make it "Ghost" in
the Logic Buttons F4. As soon as a character touches the water it will drown.
Similar - working are game objects with the "kill" Property. When touching the character will loose life energy
until he dies.
You can now start adding more objects and maybe sheep, rats or whatever and start to design your own "Yo
Frankie!" Level.
Modify Apricot Files
If you like to make a new game or at least to change vital parts of "Yo Frankie!" then it is recommended to
copy the whole folder tree to your disk and work in there. Save changes to the files into a new file, so that
your changes don't interfere with the original levels.
My goal is to make a special butterfly level, where Frankie only has to collect butterflies.
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Apricot OpenGame Project: Yo Frankie!
Modify Apricot Files
□
First I loaded the butterfly (Blends/YoFrankie/chars/butterf lyl .blend) and saved it under a
new name. First thing we have to do is to switch of (set to "False") the Property "pickup". We will handle our
things ourself here. Now locate the Keyboard Sensor and change it to a Collision Sensor. Enter "predator" in
the Property field, so it will only react on collisions with a main character.
In the Ray Sensor "above_any thing" we can now lower the Range value, so that Franky can reach a flying
butterfly with a normal jump.
Beside that I am sending a message with the subject "Butterfly", so we can count the score.
For a mean effect I also added a single butterfly-wing and will add it to the scene when the butterfly is caught.
Next I modified Frankie.blend. I don't want to use the (quite complex) HUD overlay which comes with
Frankie. So I simply deleted the name "hud" in the Scene Actuator. This one is a bit hidden in the complex
logic of Frankie. It is on the object "Main Cam" and you need to make the logic bricks visible by clicking on
the name "Main Cam".
□
We are now ready to test our modified files. Make a simple level, don't forget to add the "ground" Properties
to the ground objects and use the "init_options.py" script to initialize the player. Now add a main Character
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Apricot OpenGame Project: Yo Frankie!
and some butterflies. You should now be able to catch the butterflies.
Modify Apricot Files
□
With a simple logic you are now able to count the score when the option "Show Debug Properties" in the
"Game"-menu is activated.
I also added a own HUD for displaying my "kill count" and dropped in some props from the game. This was
all done in a couple of hours, sure I am not th greatest level designer, but however, without the help of all the
production data I could never made such a visually appealing game in such a short time. It takes much longer
to make a level playable or fun, but with the latest developments we unlock Blender for the artists more and
more, you don't need to be a developer anymore for such kind of stuff.
You can see that it needs some exploration and coming with that a deeper understanding of the complex
coherences of the "Yo Frankie!" files, but the reward is high, you look behind the scenes of a professional
done game. Be sure to check out all the other files and tutorials on the "Yo Frankie!" DVD.
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Reference
The reference section will be your guide to exploring the Blender 3D game engine further after following the
tutorials. To learn modeling and linear animation refer to the books mentioned in the appendix.
Real-time Materials
'imeiine
□
Game menu material options
There are different options on how to use materials for real time-content in Blender. All different kinds have
specific advantages and disadvantages. The material system in Blender is now nearly complete usable in the
game engine, however these materials need a good graphics cards.
Because of the deep impact on the speed of your game you probably need to make a decision what kind of
material you want. In the Game menu you will find options to switch between the materials.
The following sections will explain the material options in the Game-menu.
Texture Face Materials
Texture Face Materials are the most basic materials in the game engine. Basically they only provide basic
Materials (color) or one texture.
Features like lighting, specularity, hardness are working on vertex level so for low poly objects you will see
artifacts in the lighting or in the specularity spot.
For a basic material, add a new one in the Material Buttons F5 or choose an existing one. Then change colors
or other attributes. The object will be lit according to the lights (see also #Lamps in the game engine ) in the
same layer.
To add a texture we have to use UV texturing, see #UV Texturing . The texture will be mixed with the material
color (only in the game engine not in the 3d view). To get vertex lighting we need to set the faces to "Light" in
the Texture Face Panel in the Edit Buttons F9. Use the "Copy"-button to copy the Active Face Mode from the
active to all selected faces. Beside the mixing with the plain material color it is also possible to use
vertex-colors, see #Vertex Paint .
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Reference
Blender Multitexture Materials
Blender Multitexture Materials
With these materials it is possible to have more up to three texture channels on an object. These textures can
mix in different kind of ways. This makes it possible to have simple pre rendered light maps or faked
reflections (using EnvMaps). Especially helpful is the possibility to bake the render into the texture, this can
be done in the "Render"-menu.
Lighting, specularity, hardness for Blender Multitexture Materials is calculated on vertex level.
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You need to add a material with more than one texture channel. Then assign two or three textures to it, set the
texture blending mode to one of the supported modes: Add, Multiply, Subtract, Divide or Mix. For Mix you
need to adjust the Col: slider too.
Be sure to uncheck "UseAlpha" in the texture or the mixing will not produce the correct results!
The texture coordinates should come from one ore more UV Textures, which you can add and manage in the
Edit Buttons F9, "Mesh"-panel.
Examples:
• Multitexture. blend (the supported mixing modes)
GLSL Materials
. i . k* i B^K
□
Blenders GLSL Materials are the newest development for real time 3D and interactive display in the
3DViews. In the game engine you exactly get what you see in the 3D Views and it even almost looks like
rendered. The purpose of this system is to stick closely to the material system as in Blender's internal renderer.
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144
Reference GLSL Materials
Only a subset of the material options are supported, with hopefully more in the future, but the ones that are
supported should give nearly identical results. Some advanced features like ray tracing are not likely to be
added given that graphics card don't support them efficiently yet.
The main supported features are:
• All material diffuse and specular shaders.
• Diffuse and specular ramps.
• All nodes, except for the dynamic node and limited support for material node.
• Image textures only with few options.
• A subset of the texture mapping options.
• All lamp types except area, and basic support for shadow buffers.
• Unlike Multitexture materials, most material and light settings are currently not animateable with
GLSL materials. The limitations:
• All objects will compute the lighting for all lamps, even if they are far away or on another layer.
Hence it is important to keep the number of lamps as low as possible. For example for outdoor scenes,
two sun or hemi lamps can illuminate the whole scene already.
• The game engine supports maximum two UV layers and no compatible Oreo texture coordinates.
GLSL Materials Performance Tips
Since Blender's materials system was designed for off line rendering and the GLSL materials attempting to be
compatible with the internal render, they may not render as fast as more optimized game engines. Therefore it
is important to optimize the material and light settings for best performance:
• If some settings are set to values like 0.001 or 0.98, the visual difference with settings 0.0 or 1.0 may
be very small, but it makes it harder for Blender to optimize the shader. Therefore it is advised to set
such settings to 0.0 or 1.0 so that the effect can be completely disabled and does not need to be
computed at all.
• Various material shaders are supported, but may perform very slow. Lambert and Phong are fastest,
so if possible those should be used. Note that for specularity Cook Torr is the default, which can in
many cases be switched to Phong without much difference.
• Additionally it helps to disable specularity if it is not needed. Not only can the Spec value be set to 0.0
in materials, but it also helps to enable No Specular on lamps, so only one lamp affects specularity for
example.
• If an image does not have alpha, it can help to disable Use Alpha in the texture buttons.
• Avoid slow texture or ramp blending modes, mix/add/subtract/multiply are the fastest,
hue/saturation/value/color are very slow.
• Alpha blending needs to be avoided if possible, and Clip Alpha is a faster alternative, see the #Game
Engine Alpha Blending for more information.
• For shadows, it is more efficient to bake them for the whole scene, and use an OnlyShadow spot lamp
for the character. On this spot lamp it is best to set the shadow buffer size low, enable No Specular,
set SpotBl to 0.0. Also then the Layer option for shadow can be enable so that the lamp only casts the
shadow of the character.
Graphics Card Support
This implementation takes advantage of the OpenGL Shading Language (GLSL), and requires a graphics card
and drivers that support it. The game engine already supported such GLSL shaders, though they had to be
manually written. The following cards typically support it, though the earlier ones have restrictions on the
complexity of materials and the number of lights. Be sure to install the latest graphics card drivers as they
might fix bugs and improve performance.
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Reference GLSL Materials
• ATI Radeon 9x00, XxOO, XlxOO, HD2x00 and HD3xOO series and newer.
• NVidia Geforce FX, 6x00, 7x00, 8x00, 9x00 and GTX 2x0 and newer.
Intel or VIA graphics cards, ATI Radeon cards older then the XxOO series, and Nvidia Geforce cards older
than the 6x00 series are unlikely to support this functionality well, unless through a slow software fall back.
The game menu provides settings to disable things such as lights, advanced shaders or shadows which can
help on older graphics cards or complicated scenes.
Game Engine Alpha Blending
Transprarent faces are always expensive in a real time environment. Therefor there are different modes which
all have their limitations but differ in rendering speed.
For clarity, here is an overview of alpha sorting in the game engine, there are four transparency types in the
game engine:
• Opaque: solid, no transparency at all.
• Alpha: transparency with values between 0-1, blends with faces behind it.
• Add: like Alpha, but adds color rather than blends.
• Clip Alpha: otherwise known as binary alpha, each pixel renders either completely opaque (when
alpha > 0.5) or completely transparent (alpha <= 0.5).
Ideally one would not have to deal with such settings, but for good performance it is important to pick the
right ones, since rendering with Alpha isn't as fast as Opaque. In many cases Clip Alpha can be used instead
of Alpha while still being nearly as fast as Solid. For example for leaves one usually does not need partial
transparency.
Dbhuc r J.JJ ■.:„:,„
□
These settings can be set per face in the Texture Face panel. Note that for GLSL materials, the ZTransp
setting must be used to enable any alpha, consistent with the internal render engine. The Alpha/ Add/Clip
Alpha settings can then be used to specify the exact blending type.
One important thing to know is that for rendering faces with Alpha and Add correct, the faces must be sorted
before rendering in every frame. This is only supported in the game engine, not in the Blender viewport,
which means that faces with alpha will draw incorrect in some cases there. Clip Alpha does not require
sorting, which is useful since sorting objects with many polygons is slow.
Sorting has to be enabled with the Sort option in the Texture Face panel. The reason alpha sorting has to be set
separately is because of the performance hit, and some objects might still render OK without sorting, so it is
not enabled by default.
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Reference
Lamps in the game engine
Lamps in the game engine
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Lamps are created with the Toolbox (SPACE->Add Lamp) you can then choose the type of the lamp.
For a selected lamp you can switch to the Lamp Buttons (F5) to change the properties of that lamp. These
properties are the type of the lamp, the color, the energy, etc. Due to the fact that the game engine is fully
integrated in Blender, there are some buttons which are only useful for linear animation.
Common settings for all lamp types are the energy, and the color (adjustable with the RGB sliders).
To allow a face to receive real-time lighting in Blenders game engine, the face has to be set to "Light" in the
"Texture Face"-panel. With the layer settings for lamps and objects (Edit Buttons, F9) you can control the
lighting very precisely. Lamps only affect faces on the same layer(s) as the lamp. Per Layer you can use eight
lamps (OpenGL limitation) for real-time lighting.
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Lamp types for the game engine
Lamp: Lamp is a point light source.
Spot: This lamp is restricted to a conical space. In the 3DView the form of the spotlight is shown with broken
lines. Use the SpotSi slider to set the angle of the beam.
Sun: The "Sun" lamp type is a directional light. The distance has no effect on the intensity. Change the
direction of the light (shown as a broken line) by rotating the lamp.
Hemi: Only supported with GLSL Materials! A "Hemi" lamp is a 180A° constant light source. Great for fill
light.
The "Lamp" and "Spot" lights can be sensitive to distance. Use the "Disk", "Quadl:" and "Quad2:" settings
for this.
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Reference
GLSL Shadows
Lamps in the game engine
Dynamic shadows (moving objects or lamps) in the game engine are possible with GLSL Materials and Spot
Lamps. Static shadows can be realized using light mapping techniques.
First enable GLSL Materials in the Game menu. Then assign a Blender Material to all the shadow receiving
objects. Enter the Textured Mode with ALT-Z.
Use a Spot with "Buffer Shadow" enabled as lamp. Set the size of the spot (SpotSi) according to your scene.
Note that shadow lamps can easily decrease the speed of your game. If your shadow is too jagged like in the
image [!below], then you might increase the ShadowBufferSize. Try to keep both values as low as possible.
□
Bias: If the shadow is only partially visible or parts of your object don't cast a shadow on the object itself,
then decrease the "Bias:" value.
Only Shadow: In some situations it is nice to have a shadow but avoid illumination caused by the lights
source itself. Examples are character shadows where the shadow gives a visual hint how high a character is
while jumping for example.
Use the "Layer" option (see below) in the "Shadow and Spot" Panel to avoid that other objects interfere with
the characters shadow. If your character needs to rotate use Vertex Parenting to attach the lamp.
Layer Buttons:
• Layer in the "Lamp"-panel: This lamp only shines on objects in the same layer(s) as the lamp. Also
shadows are only received from this lamp if the object shares the layer with the lamp.
• Layer in the "Shadow and Spof'-panel: Only Objects in the same layer casting shadow from this
lamp.
Examples:
• GLSL_Lamps.blend
• GLSL_LayerLamps.blend
• GLSL_Lamps_Bias.blend
• GLSL_Lamps_OnlyShadow.blend
UV Texturing
The UV editor is fully integrated into Blender and allows you to uv-map textures onto the faces of your
models. Each face can have individual texture coordinates and an individual image assigned. This can be
combined with vertex colors to darken or lighten the texture or to tint it.
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UV Texturing
UV Mapping is the art of mapping a 2D image around a 3D object with few distortions as
possible !
With GLSL Materials now nearly the whole material system is available in the game engine. However this
also needs some attention with textures. For now it is not so simple as with the old Texture Face Materials to
get two images on different faces on one object. With GLSL we need multi-materials for that.
For UV mapping you enter EditMode for your object (only mesh objects supported). It is recommended to use
the Face Select Mode in the EditMode, however it is perfectly ok to select faces by selecting 3 or 4 vertices or
3 or four edges. All the powers of EditMode are usable (i.e. Border Select, Circle Select, see also the
Select-menu).
We now need a UV coordinate for the object. This can be achieved in some ways depending on the way you
work or what you prefer:
• select faces, then assign or load an image in the UV/Image Editor
• use "New" in the "Mesh"-panel in the Edit Buttons F9 to make a new UV Texture
• unwrap the object using UKEY
Face Specials
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□
STRG-F calls the "Face Specials"-menu
Important functions for UV mapping here:
• Face Mode Set/Clear: setting the face modes, like Tex, Tiles, Light, Invisible, Collision etc. This can
also be done in the "Texture Face"-panel in the Edit Buttons
• UV Rotate/Mirror: Rotate/mirror the texture-coordinates
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Reference UV Texturing
□
In the "Texture Face"-Panel of the Edit Buttons F9 you will find these functions also, and more:
Face modes
Tex
This enables the use of textures. To use objects without textures, disable "Tex", then the material
color will be used or paint the faces with VertexPaint.
Tiles
This indicates and sets the use of the tile mode for the texture, see Section #Texture Tiles
Light
Enables real-time lighting on faces. Lamps only affect faces of objects that are in the same layer as
the lamp. Lamps can also be placed on more than one layer, which makes it possible to create
complex real-time lighting situations. See also Section #Lamps in the game engine
Invisible
Makes faces invisible. These faces are still calculated for collisions, so this gives you an option to
build invisible barriers, etc.
Collision
The faces with this option are evaluated by the game engine. If that is not needed, switch off this
option to save resources.
Shared
With this option vertex colors are blended across faces if they share vertices.
Twoside
Faces with this attribute are rendered two sided in the game engine.
ObColor
Faces can have color that can be animated by using the ColR, ColG, ColB and ColA Ipos. Choosing
this option replaces the vertex colors.
Halo
Faces with this attribute are rendered with the negative X-axis always pointing towards the active
view or camera.
Billboard
Faces with this attribute are pointing in the direction of the active view with the negative X-axis. It is
different to "Halo" in that the faces are only rotated around the Z-axis.
Shadow
Faces with this attribute are projected onto the ground along the Z-axis of the object. This way they
can be used to suggest the shadow of the object without using expensive real-time shadows.
Text
Faces with this attribute are used for displaying bitmap text in the game engine, see Section #Bitmap
Text
Sort
Enable sorting of faces for correct alpha drawing. Note this is slow, use Clip Alpha whenever
possible!
Opaque
Normal opaque rendered faces. The color of the texture is rendered as color.
Add
Faces are rendered transparent. The color of the face is added to what has already been drawn. Black
areas in the texture are transparent, white are fully bright. Use this option to achieve light beam
effects, glows or halos around lights. For real transparency use the next option "Alpha".
Alpha
The transparency depends on the alpha channel of the texture.
Clip Alpha
The transparency depends on the clipped alpha channel of the texture. (See also #Game Engine Alpha
Blending )
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UV Texturing
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□
The "Copy" buttons will always copy the Face Modes from the active face (dotted highlight) to the selected
(pink highlight) faces. "CopyUV", "CopyTex" and "CopyColor" are copying UVs, texture and color from the
active face to the selected faces.
In the "Copy Face Selected" menu called by CTRL-C you find more helpful functions to copy face properties.
Unwrapping
Unwrapping helps you to find a mapping from the 2D image to your 3D Object. A plane or a cube are easy to
map, but with more organic and round objects like bottles, spheres or faces you need help in unwrapping.
Usually the automatic unwrapping is the base and the artist then optimizes the result.
The UV Calculation menu is called out of Edit Mode with UKEY, all selected Faces are taken into
calculation.
UV Calculation
Unwrap
Cube Projection
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Project Fram view
Project from view (Sauna's)
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Follow Active (quad$)
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Unwrap
Unwraps the object taking seams into account
Cube Projection
Cubic projection (good base for walls, houses, technical devices)
Cylinder from View
Cylindrical projection (bottles, tires)
Sphere from View
Spherical projection (planets, marbles)
Project from View
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UV Texturing
The UV coordinates are calculated using the projection of the 3DWindow (good base for manually
tweaking the result)
Project from View (Bounds)
The UV coordinates are calculated using the projection of the 3DWindow and then scaled to fit into
the image dimensions.
Reset
Resets the UV coordinates of the selected faces
Click project from face
With three mouse clicks you can interactively set the uv coordinates in the 3DView
Follow Active (quads)
The quads of an object are unwrapped. Good for complex rectangular buldings. With the option
"Loop Average" the face areas will be taken into account.
Lightmap UVPack
Method to unpack complex objects to use the map for light maps.
Unwrap (smart projections)
Powerfull unwrap method for mechanical and architectural objects.
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UV Calculation
Image Aspect
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□
In the "UV Calculation"-panel of the Edit Buttons F9 you can fine tune some parameters for unwrapping.
Image Aspect
Scales the unwrapping to the texture aspect
Transform Correction
With this option, the UV stays intact during an edge slide
Cube Size and Cyl Radius
Adjusts the size or radius for cubic or cylindrical unwrapping
Unwrapper (Conformal/Angle Based)
Unwrapping method
Fill Holes
Fill holes to prevent overlaps inside the unwrap
View Aligns Face/Top/Obj
Align the sperical/cylindrical unwrapping to the equator, pole or to the object align itself
Polar ZX/ZY
Polar is X or Y for cylindrical or spherical unwrap
Seams
Seams are important for a good unwrapping. They define the edges where the unwrap algorithm is "cutting"
the mesh apart. Place seams so that they are not noticeable or at a place where the material or texture changes
much. Try to match the face areas in the projection with the faces of the 3d object.
Select the edges you want the seam to be and do CTRL - EKEY -> Mark Seam. To clear a seam use CTRL -
EKEY -> Clear Seam.
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Reference
UV/lmage Editor
Anatomy of the UV/lmage Window:
UV Texturing
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View menu
Basic functions for the window, including zoom, maximize etc.
In the View Properties panel you can find nice functions to help you while working with UVs. Deactivate the
"Face"-button to switch of the display of faces which can occlude your sight on the object and the image.
"Repeat Image" helps you with tiling the image on the objects faces. "UV Stretch" will give you a visual hint
how much your image gets distorted. Also note the possibility to set and read the position of the 2D Cursor.
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Reference UV Texturing
Image menu
Basic image functions for load, save, pack etc. Also place for Python helper scripts.
Select menu (only availble when the mesh is in EditMode)
This menu contains special selection methods.
UVs menu
This menu contains many useful functions for working with UVs. It is beyond the scope of this chapter to
explain everything here.
Working with UV Coordinates
As soon as you have a UV Texture on your object, you can work with it in the UV/Image Editor. UV vertices
are represented with yellow (selected) or pink (unselected) points, connected by lines , just like in EditMode.
There are almost the same tools to work with the UV vertices as you are used to from the EditMode. Grab
with GKEY, rotate with RKEY, scale with SKEY etc.
Unlike in meshes all UV faces (triangle or quad) have their own vertices, there is no sharing between vertices,
because we need to be able to move any faces where ever we want. However, because it is often needed to
move vertices together, an option is enabled by default to stick vertices together for easy editing. You can
choose this behavior in the UV/Image Editor header:
□
Shared Vertex
This will stick 3d vertices which are shared by face in the mesh. Usually you don't want to separate
such vertices in the UV coordinates, because this will generate seams in the texture on the object.
Shared Location (default)
Vertices in the UV coordinates will be moved together when they share the same place (in a 5 pixel
range)
Disable
Move vertices freely
Texture Tiles
Texture Tiles can be used to have more textures in one image an still be able to repeat textures on the objects.
This is quite useful to save texture memory on older systems. The other use is to have simple animated
textures.
Load a tiled texture into the UV/Image Editor, unwrap your object and assign the texture. Open the "Real-time
Properties" -panel in the View-menu.
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UV Texturing
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□
Now set "X:" and "Y:" according to the number of tiles in your texture and activate "Tiles". In EditMode you
can now select the tile you want to use with SHIFT-LMB from the texture. It is now possible to use the
normal UV editing tools and so for example scale up to have the tile repeated on your object.
For a simple texture animation you load a tiled texture on your object, then also set "X:" and "Y:" according to
the number of tiles in your texture, no need to activate "Tiles" this time. Instead activate "Anim" and set the
"Sta:" and "End:" to the desired values (End = X * Y). Finally set the speed (in frames per second) of the
animation with "Speed:". You should now see a texture animation in your game. For a GLSL Material you
also need a Blender Material and a Texture with your animation, then you could for example animate a Nor
map to get real ripples on your water object.
Texture Tiling Animation only works for Texture Face Materials and GLSL Materials.
Examples:
• TextureTiling.blend
• TileAnim.blend
• TileAnimGLSL.blend
Bitmap Text
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Blender has the ability to draw text in the game engine using special bitmap fonts textures. These bitmap fonts
can be created from a TrueType or a Postscript outline font. See JTJ for how to make your own. On DVD are
some textures with bitmap fonts to try.
To get bitmap text or numbers displayed on a single face you need a special bitmap with the font rendered
onto it. UV map the first character ("@") of the text-bitmap onto your text object (usually a plane). In the
"Texture Face"-panel in the Edit Buttons F9 activate "Text" for all faces of your text object.
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UV Texturing
Then create a property named "Text" for your object. The property can be any type, so a Boolean Property
will also be rendered as "True" or "False". For testing use a String -property and enter some text. Then start the
game engine to see the results.
Vertex Paint
□
Vertex Paint Panel in the Edit Buttons F9
To start VertexPaint press VKEY or select the VertexPaint mode in the 3DView Header. The selected object
will now be drawn solid. You can therefore now draw on the vertices of the object while holding LMB, the
size of the brush is visualized by a circle while drawing. RMB will sample the color under the mouse pointer.
Enter the Edit Buttons F9 to see the aVertexPainta-panel. Here you can also find more options to control
VertexPaint:
R, G, B: The active color used for painting. Can also be set by using the Color Picker called by a LMB-click
into the color field (see below)
Opacity: The extent to which the vertex color changes while you are painting.
Size: The size of the brush, which is drawn as a circle during painting.
Paint Modes
□
Mix
Add
The manner in which the new color replaces the old when painting: the colors are mixed.
The colors are added.
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Sub
UV Texturing
Mul
Blur
Lighter
The paint color is subtracted from the vertex color.
The paint color is multiplied by the vertex color.
Blurs the color according to the surrounding colors
Paint over darker areas only
Darker
Paint over lighter areas only
Color field: A LMB click calls the color picker
SetVCol: Sets all vertices to the chosen color
All Faces: Paint on all faces inside the brush
VertexDist: This specifies that the extent to which the vertices lie within the brush also determines the brush's
effect.
Normals The vertex normal (helps) determine the extent of painting. This causes an effect as tough you were
painting with light.
Spray: Continues to add color while holding LMB and moving the mouse
Set: The "Mul" and "Gamma" factors are applied to the vertex colors of the Mesh.
Mul: The number by which the vertex colors are multiplied when "Set" is pressed.
Gamma: The number by which the clarity (Gamma value) of the vertex colors are changed when "Set" is
pressed. You can choose on which faces you like to paint with the Painting Mask, called by FKEY or the icon
\M] in the 3DView header. You can now select faces with the RMB, SHIFT-RMB, Border- or Circle-Select.
Painting will now only occur on the selected faces. When the Painting Mask is active, you can choose with the
Buttons "Faces", "Edges" and "Hidden Edges" how the faces or edges should be displayed while painting.
This especially helps while staring to paint on a solid colored object.
Texture Paint
□
To start Texture Paint select the Texture Paint Mode in the 3D Window header or out of the UV/Image Editor.
Depending from where you activated Texture Paint you are now ready for painting either in the 3D View on
your objects, or in the UV/Image Editor on your texture.
Texture Paint needs a UV textured object to work. You also need to unpack a packed texture first.
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UV Texturing
In the UV/Image Editor you paint like in a 2D paint application, in the 3D View you actually painting on the
3d object depending on ho the faces are oriented in 3D space.
You can now paint holding the LMB. RMB will sample the color located under the mouse pointer.
In the 3D View you can call the "Paint Properties" -panel with NKEY. Here you can adjust the color. Using
the FKEY you can switch on a paint mask, meaning you can only paint on the selected faces. Faces are
selected like in Edit Mode, RMB selects, SHIFT-RMB adds, you can also use Border Select or Circle Select.
In the "Painf'-panel in the Edit Buttons F9, you can also choose between different paint modes and mix
modes. Further you can adjust the opacity, size, falloff and spacing of you brush strokes. It is also possible to
add or recall brush settings or to paint using a different texture.
The "Image Painf'-panel has similar options. But aside of that you can also clone draw a different texture onto
your texture.
Resource Handling
For publishing and easier handling of Blender's files, you can include all resources into the saved file.
Normally textures, samples and fonts are not included in a file while saving. This keeps them on your disk and
makes it possible to change them and share them between files. But if you want to distribute a file it is
possible to pack these resources into the Blendfile, so you only need to distribute one file, preventing missing
resources.
The functions for packing and unpacking are summarized in the "External Data"-menu. You can see if a file is
packed if there is a little "parcel" icon to the right in the menu bar. After you packed a file, all new added
resources are automatically packed (AutoPack).
When working with textures, sounds or fonts you will notice a pack-icon near the File- or Datablock-Browse.
This icon allows you to pack/unpack the file independently.
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UV Texturing
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External Data menu entries
Pack into .blend file
This packs all resources into the Blendfile. The next save will write the packed file to disk.
Unpack into Files
This unpacks all resources to the current directory. For textures a directory "textures" is created, for
sounds a "samples" directory and fonts are unpacked to "fonts".
Unpack3 files
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Write files to current directory (overwrite existing flies)
Use flies in originai location (create when necessary)
Write files to original location (overwrite existing files)
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□
A menu will request further options. Be careful with the options overwriting files.
Use files in current directory
This unpacks only files which are not present in the current directory. It creates files when necessary.
Write files to current directory
This unpacks the files to the current directory. It overwrites existing files!
Use files in original location
This uses files from their original location (path on disk). It creates files when necessary.
Write files to original location
This writes the files to their original location (path on disk). It overwrites existing files!
Disable AutoPack, keep all packed files
This disables AutoPack, so new inserted resources are not packed into the Blendfile.
Ask for each file
This asks the user for the unpack options of each file.
Make all Paths Relative
This option changes all file paths so that they address the file in a relative way. So you can move your
scene between different computers without caring for drives letters or such.
Make all Paths Absolute
This makes all paths absolute.
Report Missing Files
Reports missing files. A text buffer "missing_files.log" is created and contains informations about the
missing files.
Find Missing Files
With this option you can point Blender to a directory containing the missing files.
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Blenders Game Engine
Blenders Game Engine
Technically speaking the Blender game engine is a framework with a collection of modules for interactive
purposes like physics, graphics, logic, sound and networking. Functionally the game engine processes virtual
reality, consisting of content (the world, it's buildings) and behaviors (like physics, animation and logic).
Elements in this world - also called GameObjects - behave autonomously by having a set of tools called Logic
Bricks, and Properties. For comparison, the Properties act as the memory, the Sensors are the senses, the
Controllers are the brain and the Actuators allow for actions in the outside world (i.e. muscles).
At the moment, the Controllers can be scripted using python, or simple expressions. The idea is that the
creation of logical behavior can be edited in a more visual way in the future, so the set of controllers expands
with AI state machines, etc. Controllers could be split in control centers, like an audio visual center, motion
center, etc.
In fact Blender contains two game engines. One is the older and depreciated engine called "Sumo" and the
new game engine internally called "Ketsji". Sumo is still integrated inside Blender to enable older games to
run. The new engine is accompanied by a physics engine called "Bullet" (Author Erwin Coumans also know
as one of the original authors of "Ketsji", see [21) which calculates the physical behaviors of the objects, like
falling, forces and collisions.
Options for the game engine
Help
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Start Game
Starts the game, shortcut is PKEY. If there is more than one 3dView the cursor changes into a
question mark and you can now choose the view the game should be started in.
Enable All Frames
Normally the game engine will try to play the game in 60 frames per second (fps), if the CPU or
graphics power is not high enough the engine will start dropping frames to maintain the overall speed
of objects. This can cause stutter in the playback or even cause errors in collisions. With "Enable All
Frames" the movement of the objects will slow down, but no frame will be dropped. This option is
also very useful when using the game physics for linear animation.
Generate Display Lists
This option can improve the performance of the game (esp. in big and complex levels) quite a lot.
However on older graphics cards this can lead to errors.
Record Game Physics to IPO
The movements of game objects will be recorded into Ipo animations. Very helpful for complex
physics based animations (rolling, falling, jumping, collisions etc.)
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Reference Options for the game engine
Show Framerate and Profile
This will display statistical informations during game play. Good for optimizing your game.
Show Physics Visualization
This option draws objects bounds and also shows the status of physical objects. Good for debugging
and testing physics.
Show Debug Properties
This option enables the display of properties with the debug "D" button set in textured views.
Wireframe and solid shaded views always display debug properties.
Texture Face Materials
Most basic material and texture system in Blender. See #Real-time Materials .
Blender Multitexture Materials
Advanced use of multiple textures for games. See #Real-time Materials .
Blender GLSL Matrials
Up to date material system. Requires modern graphics cards. See #Real-time Materials .
GLSL Material Settings
In the sub menu you can enable/disable features of the GLSL material system for performance
reasons or compatibility with graphics cards.
Autostart
A .blend-file with this option will autostart the game after loading. To edit such a .blend you can
prevent autostart with a command line option.
Other Game Engine Options
In the User Preferences window you will find some more options:
Mipmaps
Mip-mapping is a texture filter to avoid flickering in textures and to enhance performance, especially
when viewed from distance or a flat angle. In some cases this filtering can be unwanted or can even
cause a performance drop, so this can be disabled here.
Disable Game Sound
Disable game sound, helpful to avoid errors on computers without sound hardware.
GL Texture Clamp
With these options you can force textures to a specific size. This can help to enhance the performance
on slow computers or older graphics cards.
Logic Buttons
The Logic Buttons are meant for making interactive 3d worlds in Blender. Blender is a complete development
tool for interactive worlds including a game engine to play the worlds. All this is done without compiling the
game or interactive world. Just press PKEY and it runs in real-time. The main window for working with the
Blender game engine are the Logic Buttons F4 (1®J). Here you define your Logic Bricks, which add the
behavior to your objects.
The word "games" is here used for all kinds of interactive 3D-content; Blender is not limited to making and
play games, you can also do for example scientific visualizations or interactive 3d-manuals.
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Logic Buttons
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The Logic Buttons can logically be separated in two parts. The left part contains global settings for
GameObjects.
This includes settings for general physics, like the damping or mass. Here you also define wether an object
should be calculated with the build-in physics, as an actor or should be handled as an object forming the level
(like props on a stage).
Settings for GameObjects:
With the menu button defaulting to Static you can choose how the physics engine should thread your object:
No collision No collision detection for the whole object. Use this for objects which can never be touched by
any dynamic object to save performance.
Static This object acts as surrounding for a level or as a prop (like on a stage). These objects are still movable
with Logic Bricks or Ipos, dynamic objects will react on collision with them.
Dynamic These objects will follows the laws of physics, like falling, bouncing and colliding
Rigid body This option enables the use of advanced physics by the game engine. This makes it possible that
spheres roll automatically when they make contact with other objects and the friction between the materials is
non-zero. Other shapes will tip over, tumble etc.
Soft Body This makes an object a soft body.
If you only see few buttons, one labeled "Physics" you need to create a world in the Shading Context
F5, World Buttons which also creates a physics environment.
The "Advanced" button will call a pop up which covers advanced settings for the chosen object type.
Depending on the object type other buttons will appear:
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Reference
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Logic Buttons
Actor This makes Static objects detectable for Near and Radar sensors. Dynamic and Rigid Body objects are
always an actor.
Ghost Ghost objects that don't restitute to collisions, but still trigger a collision sensor.
Advanced Settings Clicking on this button will call a pop-oup menu containing advanced settings for the
choosen object type. For dynamic objects it will contain
Margin Each physics object has a collision margin in which collisions are detected. This margin leads
to a much more stable simulation. However, for small objects or special cases you might want to
decrease this margin to avoid gaps between resting objects.
Clamp Velocity (except when totally still) with a minimum and maximum value (0 = disabled).
Mass The mass of a dynamic actor has an effect on how the actor reacts when forces are applied to it. You
need a bigger force to move a heavier object. Note that heavier objects don't fall faster! It is the air drag that
causes a difference in the falling speed in our environment (without air, e.g. on the moon, a feather and a
hammer fall at the same speed). Use the "Damp" value to simulate air drag.
Radius The size of the bounding sphere for sphere bound objects. The bounding sphere determines the area
with which collisions can occur.
No sleeping Disable auto (de)activation for dynamic objects. Usually a object will be deactivated until it gets
moved or hit by another object to save performance. For character objects this behavior can be unwanted.
Damp General (movement) damping for the object. Use this value for simulating the damping an object
receives from air or water. In a space scene you might want to use very low or zero damping, air needs a
higher damping, use a very high damping to simulate water.
RotDamp Same as "Damp" but for rotations of the object.
Do FH The FH system allows floating and hovering objects. Use together with the FH settings in the DYN
Materials section.
Rot FH Uses the fave normal of the ground object to rotate the object.
Anisotropic Anisotropic friction. This enables different friction along the axes of an object. Great for
sliding/skiing etc.
For the advanced settings for soft body objects please look in the soft body section.
With the "Bounds"-button you can activate other bounds types than the default bounding-sphere:
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Box Bounding box around the objects extends.
Sphere or default (no Bounds button activated)
Spherical bounds, visualized by a dotted circle in the 3DView. The Radius can be changed in the
"Radius:" field.
Cylinder Cylindrical bounds, good for wheels, bottles, cans etc.
Cone Cone shaped bounds.
Convex Hull Convex (outward bulging surface) hull around the actual shape of the object. No holes or inward
bulges are calculated.
Triangle Mesh This makes concave objects possible, for performance it is still recommended to use
compound objects
Compound Adds dynamic children (parented with CTRL-P to the main object) to the physics calculation
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Properties
Below the object settings you define the Properties of a GameObject. These Properties can carry values,
which describe attributes of the object like variables in a programming language. Use "ADD property" to add
properties.
Properties
Properties carry information bound to the object, similarly to a local variable in programming languages. No
other object can normally access these properties, but it is possible to copy Properties with the Property
(Copy) Actuator (see #Property Actuator ) or send them to other objects using messages (see #Message Body ).
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The big "ADD property" button adds a new Property. By default a Property of the float type is added. Delete a
Property with its "Del" button. The Menu Button defines the type of the Property. Click and hold it with the
left mouse button and choose from the pop up menu. The "Name:" text field can be edited by clicking it with
the left mouse button. SHIFT-BACKSPACE clears the name. Important
Property names are case sensitive. So "Benoit" is not equal to "benoit".
The next field is different for each of the Property types. For the Boolean type there are two radio-buttons;
choose between "True" and "False". The string-type accepts a string; enter a string by clicking in the field
with the left mouse. The other types use a Number Button to define the default value. Use SHIFT-LMB for
editing it with the keyboard, click and drag to change the value with the mouse.
Property types:
Boolean (Bool) This Property type stores a binary value, meaning it can be "TRUE" or "FALSE". Be sure to
write it all in capitals when using these values in Property Sensors or Expressions.
Integer (Int) Stores a number like 1,2,3,4,... in the range from -2147483647 to 2147483647.
Float Stores a floating point number like 3.14159265.
String Stores a text string.
Timer This Property type is updated with the actual game time in seconds, starting from zero. On newly
created objects the timer starts when the object is "born".
Example of some Logic
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Reference
Example of some Logic
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The right part of the Logic Buttons is the command center for adding logic to your objects and worlds. The
logic consists of the Sensors, Controllers and Actuators.
Sensors are like the senses of a life form; they react on key presses, collisions, contact with materials (touch),
timer events or values of properties.
The Controllers are collecting events from the sensors and are able to calculate them to a result. These are
similar to the mind or brain of a life form. Simple Controllers just do an AND on the inputs. An example is to
test if a key is pressed AND a certain time has passed. There are also OR Controllers and you can also use
Python scripting and expressions in the Expression Controller to create more complex behavior.
The Actuator actually performs actions on objects. A Motion Actuator for example is like a muscle. This
muscle can apply forces to objects to move or rotate them. There are also Actuators for playing predefined
animations (via Ipos), which can be compared to a reflex.
The logic is connected (wired) by click and hold LMB on an outlet (sphere) then dragging the mouse to the
inlet and release. Sensors to Controllers and Controllers to Actuators. After wiring you are immediately able
to play the game! If you discover something in the game you don't like, just stop the game engine, edit your
3-D world and restart. This way you can drastically cut down your development time!
The Blender laws of physics
All objects in Blender with the "Dynamic" or "Rigid Body" option set are evaluated using the physics laws as
defined by the physics engine and the user.
The key property for a dynamic object is its mass. Gravity, forces, and impulses (collision bounce) only work
on objects with a mass. Also, only dynamic objects can experience drag, or velocity damping (a crude way to
mimic air/water resistance).
Note that for dynamic objects using dLoc and dRot may not have the desired result. Since the velocity of a
dynamic object is controlled by the forces and impulses, any explicit change of position or orientation of an
object may not correspond with the velocity. For dynamic objects it's better to use the linV and angV for
explicitly defining the motion.
As soon we have defined a mass for our dynamic object, it will be affected by gravity, causing it to fall until it
hits another object with its bounding. The gravity has a value of 9.81 by default, if you use one Blender unit
as lm and the mass of 1.0 as one kilogramm your objects will almost react as in the real world. You can
change the gravitation in the World Buttons with the "Grav" slider. A gravity of zero is very useful for space
games or simulations.
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The Blender laws of physics
Damping can be used to simulate air drag. Damping decreases the velocity in percent (%) per second.
Damping is useful to achieve a maximum speed. The larger the speed the greater the absolute decrease of
speed due to drag. The maximum speed is attained when the acceleration due to forces equals the deceleration
due to drag. Damping is also useful for damping out unwanted oscillations due to springs.
RotDamp does the same like Damp, but for rotational movements.
Use the "Damp:" and "RotDamp:" settings to suggest the drag of air or other environments. Don't use it to
simulate friction. Friction can be simulated by using the dynamic material settings.
Do Fh and Rot Fh are a special way to simulate floating behaivior. Together with the dynamic settings in the
Material this can be used to make boats or hovercrafts.
For some objects you need to have different friction in different directions. For instance a skateboard will
experience relatively little friction when moving it forward and backward, but a lot of friction when moving it
side to side. This is called anisotropic friction. Selecting the "Anisotropic" button in the Logic Buttons (F4)
will enable anisotropic friction. After selecting this button, three sliders will appear in which the relative
coefficient for each of the local axes can be set. A relative coefficient of zero denotes that along the
corresponding axis no friction is experienced. A relative coefficient of one denotes that the full friction applies
along the corresponding axis.
Dynamic Settings in the Material
Some physical attributes can be defined with the material settings of Blender. The Material Buttons can be
accessed via the icon in the header of the Buttons Window or by pressing F5. Create a new material or choose
an existing one with the Menu Button in the header.
In the Material Buttons you need then to activate the "DYN" button to see the dynamic settings:
Material
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Restitute: Objects will bounce on a collision. To control the amount of bounce add a material to the objects
and set the Restitute value in the DYN section of the material to near zero for a soft material and near 1 .0 for a
very elastic material. Note that a very elastic ball will not bounce on a very soft material, so tune both
materials.
Friction: Friction is a force tangent to the contact surface. The friction force has a maximum that is linear to
the normal, i.e., the force that presses the objects against each other, (the weight of the object). The friction
value denotes the Coulomb friction coefficient, i.e. the ratio of the maximum friction force and the normal
force. A larger friction value will allow for a larger maximum friction. For a sliding object the friction force
will always be the maximum friction force. For a stationary object the friction force will cancel out any
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tangent force that is less than the maximum friction. If the tangent force is larger than the maximum friction
then the object will start sliding.
Fh Force: In conjunction with the "Do Fh" and/or "Rot Fh" in the Logic Buttons F4 you make an object float
above a surface. "Fh Force" controls the force that keeps the object above the floor.
Fh Dist: "Fh Dist" controls the size of the Fh area. When the object enters this area the Fh mechanism starts
to work.
Fh Damp: Controls the damping inside the Fh area. Values above 0.0 will damp the object movement inside
the Fh area.
Fh Norm: With this button activated the object also gets a force in the direction of the face normal on slopes.
This will cause an object to slide down a slope
Examples:
• FhDemo.blend
• Another way to have floating behaiviour is the Force Field Consraint, see ForceFieldConstraint.blend
Soft Bodies by Erwin Coumans
From Blender 2.48 onwards, the game engine features Bullet soft body simulation.
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Soft Body Features
• Flat cloth or volumetric soft bodies
• Control over mass, friction, stiffness, shape matching and collision detection settings
• Collision detection beween soft bodies as well as rigid bodies and static collision bounds of all types.
• Attaching soft bodies against rigid bodies or using fixed pinning
• Physics Debug Visualization of the dynamic soft body structures
• Dynamically create new soft bodies using the Add Object Actuator
Creating a Bullet soft body
• Choose "Soft Body" in the Logic Buttons F4
• Choose a collision shape bounds for soft bodies, the bounds types for soft bodies are automatically
restricted to convex hull or triangle mesh bounds.
Basic Soft Body Setting
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Soft Bodies by Erwin Coumans
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LinStiff: Linear Stiffness, lower values create very flexible soft bodies, and larger values (1) more stiffness.
Note that the shape matching feature and bending constraints will still keep extreme flexible bodies in shape.
Shape Match: when this option is enabled, Bullet will remember the original shape of each soft body, and
tries to match the shape of a soft body, no matter how large the deformation has been.
kMT: Shape matching coefficient, how strong the soft body will return to its original shape. This only appear
when the "Shape Match" option is enabled.
Friction allows to control the dynamic friction for soft bodies, in the range "[0..1]". 0.0 means no friction, soft
bodies will slide.
Advanced Settings
Cluster Collision RS/SS: collision clusters can improve the collision detection, and it can avoid soft bodies
passing through triangle meshes. Instead of colliding between individual vertices/nodes and faces, deformable
convex clusters can be used. You can choose to use clusters between soft bodies (SS), or between soft body
and rigid body (RS).
Cluster Iter: Higher values will create more detailed collision clusters. If you choose 1 it will use a single
cluster using all vertices. This setting is only used if Clusters RB / SS is enabled.
Position Iter: position solver iterations. Use a higher value to improve the quality of position correction for
soft bodies.
Pinning or attaching soft bodies
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Soft Bodies by Erwin Coumans
You can use the Rigid Body Joint to attach a rigid body against a soft body. Similar to rigid body constraints,
you can also pin/fix a soft body to make a vertex non-movable: just don't provide a second attachment object,
or attach to a static object.
Right now, vertex groups are not supported, so you have to use Rigid Body Joint constraints.
• Select a single soft body, or both a soft body and rigid body, using the "Add Constraint" -button in the
Object Context F7, Object Buttons, "Constrainf'-panel.
• Enable the Show Pivot to see where the soft body will be pinned (px/py/pz frame). Bullet will
automatically take the closest vertex/node to this pivot point.
• You can use multiple constraints to pin/attach multiple parts of the soft body.
• Python constraints can be used to create soft body constraints while the game is running. However,
currently you cannot remove those constraints on-the-fly.
General soft body tips and some known issues
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□
• Blender 2.48 performs no collisions between soft bodies that have Clusters enabled, and soft bodies
that have Clusters disabled. This will be fixed in future versions.
• Subdivide the soft body triangle mesh to allow some more deformation: go into Edit Mode, select all
vertices (AKEY or AKEY-AKEY) and hit subdivide.
• UV Sphere meshes are not compatible with soft bodies, so use a Ico sphere instead.
• If the mesh is too detailed, simplify the mesh using mesh decimation-modifier
• Use Show Physics Visualization to debug issues with soft bodies, collision shapes etc. Enable the
setting in the game menu.
• When running the game with Show Physics Visualization enabled, you will notice the complex
dynamic structures for soft bodies:
• Don't use scaled meshes. Instead, use the Apply Scaling feature, or Apply Scale and Rotation by
selecting the soft body object and pressing CTRL-A
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Bullet Game Engine Features
Bullet Game Engine Features
The physics engine in Blender is called "Bullet" (Author Erwin Coumans, also know as one of the original
authors of the Blender game engine, see www.bulletphysics.com ') calculates the physical behaviors of the
objects, like falling, forces and collisions. Bullet is a 3D Collision Detection and Rigid Body Dynamics
Library for games. Open Source, ZLib license, free for commercial use, including Playstation 3.
The Bullet engine is used to drive many aspects of a game like GameLogic (Ray-, Near-, Collision Sensors),
Constraints (Point, Hinge, Generic), it also contains a vehicle setup (only accessible via Python)
Bullet Physics Tips and FAQ
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Avoid Scaling
Don't scale your objects. Apply scale using CTRL-A. If you use Sphere-bounds, make sure the radius
fits the sphere
Keep masses for dynamic objects similar
If an object of 100 kg rests on an object of 0. 1 kg, the simulation will have difficulties. In order to
avoid large mass ratios, keep mass of objects similar (in the order of a few kg)
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Bullet Game Engine Features
Assign the right bounds type
For a cylinder, choose cylinder, even for non-moving objects. Similar for a box etc. Convex Hull can
approximate meshes for moving objects and static objects.
Don't use too many vertices in Convex Hull meshes
About 4 to 32 vertices should be fine. For more complex objects use simple proxy objects for the
collision margin
□
Leave the center of the object in the middle of the mesh
The center (where the axis are) needs to be inside the mesh, not near to the boundary or outside!.
Leave the gravity to 10, don't make it too large
The physics simulation works better with smaller gravity, so if possible don't use large gravity.
Avoid very small dynamic objects (< 0.2 units)
Don't make dynamic objects smaller then 0.2 units if possible. For the default gravity, 1 unit equals 1
meter, so any 'side' of the objects should be bigger then that.
No large objects
Don't use large objects, or large triangles.
Don't use degenerate triangles
Triangles that are have extreme long sides as well as extreme short sides can lead to problems.
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After a few seconds, the object doesn't move anymore. It doesn't interact with moving platforms etc.
You can manually activate an object, using python command 'object.restoreDynamics'. Or use the 'no
sleeping' button. But don't use the 'no sleeping' button too much, perhaps just for the main
character/car etc.
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Bullet Game Engine Features
□
How to setup a vehicle
Use the PhysicsConstraints module in Python, and create a special constraint on a rigid body.
• For collision Bounds it is best to use Convex Hull Polytope. Remember to switch on collision for the
chassis polygons!
• Don't use box, because shifting the center of the box doesn't work.
• Give the vehicle enough space to move: too narrow roads, too sharp corners and high street curbs and
other obstacles that are difficult to avoid are very frequent mistakes which makes driving frustrating,
rather then fun.
This constraint allows to add wheels, set tire friction, suspension, steering and so on.
There is a demo vehicle3_Steering fix.blend in the physics demos.
See the Python Vehicle Script for the code.
• To improve (vehicle) simulation quality add this line to the python scrips:
PhysicsConstraints . setNumTimeSubSteps (2 )
• don't set friction of track and ground to zero, better lower the friction of car chassis This way you can
add traffic cones and other interesting dynamic objects. Ground friction of means bad physics
quality.
• Try to tweak the form factor (under No sleeping button) a little bit, but keep it close to 0.4. For
example 0.45
• For debugging to see that the ray cast for each wheel has correct position and direction use:
fdraw the raycast lines
PhysicsConstraints . setDebugMode ( 1 )
• Make sure you don't use overlays scenes and other camera effects (split screen/viewports) during
debugging. The debug lines will not properly show up.
There is a small gap between the ground and my object
Except for boxes and sphere, there is indeed a tiny gap (0.06 by default) between objects. This gap
allows the simulation to run smoother and more stable. It is not recommended, but you can reduce the
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Reference Bullet Game Engine Features
gap with the "Margin" parameter in the Logic Buttons or using Python:
controller = GameLogic . getCurrentController ( )
owner = controller . getOwner ( )
owner . setCollisionMargin (0.01)
You can also consider using margin of zero for static/non moving objects, and leave the default margin for
dynamics objects.
I want higher quality simulation or create IPO key frames for animation
If you are on high performance machines or just rendering / creating key frames, and don't worry
about real time you can increase the sub steps to improve quality of simulation, using a python script
import PhysicsConstraints
PhysicsConstraint s . setNumTimeSubSteps (2 )
default is 1. 2 or more make simulation more accurate.
Rigid Body Joints
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Rigid Body Joints can be added in the Object Buttons F7, "Constraints"-panel. Add a "Rigid Body Constraint"
with the "Add Constraint" button. Constraints will keep a Object in a defined location or restrict the rotation
around defined axes. However be careful, it is possible to break a constraint/joint using Dloc or dRot
movements.
In common for all rigid body constraints are the position and rotation of the Pivot point (visualize with
"ShowPivot"). Enter the name of the object to constrain into the field "toObject:". disable
The "No Col." button disables the collision detection between the two linked bodies. Often the bodies are
(almost) overlapping, and collision detection conflicts with the other constraints.
Always remember that you add constraints to the parent object, not the constrained object (child)!
For debugging and visualizing a constraint it is very helpful to use the "Show Physics Visualization" from the
Game-menu.
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Sound Buttons
Joint Types
■ Generic (experimental)
Vp, Cone Twist
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With the "Rigid Body Constraint" chosen from the "Constraints"-panel you can specify different types of
constraints:
Ball
Hinge
Point to point constraint, also known as ball socket joint, limits the translation so that the local pivot
points of two rigid bodies match in world space. A chain of rigid bodies can be connected using this
constraint.
Hinge constraint, or revolute joint, restricts two additional angular degrees of freedom, so the body
can only rotate around one axis, the hinge axis. This can be useful to represent doors or wheels
rotating around one axis. The user can specify limits and motor for the hinge.
Cone Twist
To create rag dolls, the cone twist constraint is very useful for limbs like the upper arm. It is a special
point to point constraint that adds cone and twist axis limits.
Generic
A generic D6 constraint. This generic constraint can emulate a variety of standard constraints, by
configuring each of the 6 degrees of freedom (dof). The first 3 dof axis are linear axis, which
represent translation of rigid bodies, and the latter 3 dof axis represent the angular motion. For each
axis:
• Lowerlimit == Upperlimit -> axis is locked.
• Lowerlimit > Upperlimit -> axis is free
• Lowerlimit < Upperlimit -> axis it limited in that range
Examples:
• RigidBodyJointTypes. blend
• ConstraintHinge. blend
Sound Buttons
The Sound Buttons are used for loading and managing sounds for the Blender game engine. Currently only
WAV files are supported.
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Reference Performance and design issues
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Figure xx-y. The Sound Buttons
In the "Sound"-panel you can see the name of the Sound Object (here "SO:boird_flap.wav"). This name is set
to the name of the sound sample by default, you can always rename it. With the Menu Button next to the
"SO:" you can browse existing Sound Objects and load new Sound Objects. "Copy sound" makes a duplicate
of the sound.
Below the "SO:" block you can assign already loaded samples to the Sound Object. So the Sound Object
name doesn't have to be the name of the sample. For example you can use a Sound Object "SO:explosion" and
then use "explosion_nuke.wav" later. You load samples using the "Load Sample" button. Using the Menu
Button to the left of the file location, you can browse samples already loaded and assign one to the Sound
Object.
Above the sample location, Blender gives you some basic information about the loaded sample, like the
sample frequency, 8 or 16bit and if the sample is stereo or mono.
When the pack/unpack button (parcel) is pressed, the sample is packed into the *. blend file, which is
especially important when distributing files.
The "Play" button plays the sound, you can stop a playing sound with ESC. The "Vol:" slider sets the volume
of the sample. With the Pitch: value you can change the frequency of the sound. Currently there's support for
values between half the pitch (-12 semitones) and double the pitch (+12 semitones). Or in Hertz: if your
sample has a frequency of 1000 Hz, the bottom value is 500 and the top 2000 Hz.
The "Loop" button sets the looping for the sample on or off. Depending on the play-mode in the Sound
Actuator this setting can be overridden. "Ping Pong" plays the sound forwards, then backwards in a loop, great
for engine sounds.
The "3D Sound" Button activates the calculation of 3D sound for this Sound Object. This means the volume
of the sound depends on the distance and position (stereo effect) between the sound source and the listener.
The listener is the currently active camera.
The "Scale:" slider sets the sound attenuation. In a 3D world you want to scale the relationship between gain
and distance. For example, if a sound passes by the camera you want to set the scaling factor that determines
how much the sound will gain if it comes towards you and how much it will diminish if it goes away from
you. The scaling factor can be set between 0.0, all positions get multiplied by zero, no matter where the source
is, it will always sound as if it is playing in front of you (no 3D sound), 1 .0 (a neutral state, all positions get
multiplied by 1) and 5.0 which over accentuates the gain/distance relationship.
The "Listener"-panel in the Sound Buttons defines global settings for the listener. The listener is the current
active camera. The "Volume:" slider sets the global volume of all sounds. The settings for the Doppler effect
are currently not supported.
Performance and design issues
Computers get faster every month, nowadays nearly every new computer has a hardware accelerated graphics
card. But still there are some performance issues to think about. This is not only a good design and
programming style but also essential for the platform compatibility Blender provides. So to make a
well-designed game for various platforms, keep these rules in mind:
1 . Don't use properties in combination with AND/OR/Expression controller as scripting language. Use
the Python Controller for all more complex things
2. Use as few inter-object LogicBrick connections as possible.
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Reference Game Logic Bricks
3. Use ALT-D (instanced mesh for new object) when replicating meshes, this is better than SHIFT-D
(copies the mesh).
4. Alpha mapped polygons, especially sorted, are expensive, so use with care.
5. Switching off the collision flag for polygons is good for performance. The use of "Ghost" is also
cheaper then a regular physics object.
6. Keep the polygon count as low as possible. Its quite easy to add polygons to models, but very hard to
remove them without screwing up the model. The detail should be made with textures.
7. Keep your texture-resolution as low as possible. You can work with hi-res versions and then later
reduce them to publish the game.
8. Polygons set to "Light" are expensive. Use with care or use lightning baked into textures.
9. Instead of real-time lighting use VertexPaint to lighten, darken or tint faces to suggest lighting
situations.
10. Use simpler geometry for bounding and collision-bounds of objects
1 1 . Separate real time shadows to layers
12. Use GLSL Materials with care, not all graphics cards will provide them (or fall back to a slow
software rendering).
Game Logic Bricks
The game logic in Blenders game engine is assembled in the Realtime Buttons. Here you wire the different
Logic Bricks together. The following is a brief description of all the Logic Bricks currently available.
Sensors
Sensors act like real senses; they can detect collisions, feel (Touch), smell (Near), view (Ray, Radar).
Always Sensor
The most basic Sensor is the Always Sensor. It is also a good example for the common buttons every sensor
has.
X I Always
□
Always Sensor with common elements for Sensors
The button labeled "X" deletes the Sensor from the game logic. This happens without a confirmation, so be
careful. The Menu Button to the right of the delete button (here labeled "Always") allows you to choose the
type of Sensor. Click and hold it with the left mouse button to get the pop up menu. Next is a Text Button,
which holds the name of the Sensor. Blender assigns the name automatically on creation. Click the name with
the left mouse button to change the name with the keyboard. Note
Name your Logic Bricks and Blender objects to keep track of your scenes. A graphical logic scheme can
become very complex.
With the small arrow button you can hide the contents of the LogicBrick, so it only shows the top bar. This is
very handy in complex scenes. Together with the State system (see #State System) this helps to keep track on
complex logics.
The next row of buttons is used to determine how and at which frequency a Sensor is "firing". This topic is a
bit complex, so we will give examples in more than one part of this documentation.
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Reference
General things on sensors
Sensors
The internal state of a sensor can only take two values: true or false. This state value is updated at each frame
based on the external conditions that the sensor monitors: keyboard key press/release for the keyboard sensor,
mouse movement for the mouse sensor, etc. At the start of each frame, the BGE runs through all the enabled
sensors and updates their internal state. The sensor state remains unchanged through the rest of the frame
processing. Transition between true/false states is the primary cause for triggering controllers. The Lvl and
Pulse buttons can be used to generate more triggers but this is discussed in the a later section. The Inv button
inverts the internal state: when the external condition is true, the internal state is false and vice- versa.
The direction of the transition (false/true or true/false) does not matter for triggering the controllers: either
way, the controller is executed. Note that the controller is not executed immediately, but only when all
enabled sensors have been updated. Regardless if multiple sensors are triggering the same controller, each
triggered controller is executed only once. The internal state transition of a sensor triggers all the active
controllers that are attached to it.
A controller that is executed will usually check the internal state of the sensors and take appropriate action.
The logic controllers (AND, OR, XORa!) evaluate a formula using the state of all the sensors connected to
them as input values; they do not use the transition information. The Python controller runs a user provided
script and it is up to the script writer to check the state of the sensors using the Sensors aisPositive()a
function. Note that the transition information is available through the aisTriggered()a function: the script
writer can find out which of the sensor triggered the controller.
Pulse Modes and Lvl
The Lvl and Pulse buttons can be used to generate more triggers than just state transition.
111 | ... | f : Lvl | Inv |
□
Pulse Mode Buttons
There are two pulse buttons: one for the true state (left) and for the false state (right). When either button is
selected, the frequency parameter "f:" determines at which frame interval the triggers are generated. A trigger
is generated every frequency+1 frame. If the frequency parameter is 0, a trigger is generated on every frame.
If the false(true) state pulse button is selected, the repeated triggers are produced when the sensor internal
state is false(true). The pulse triggers are synchronized with the state transition: the first pulse trigger will
arrive frequency+1 frame after the state transition. If both buttons are selected, repeated pulses are produced
all the time but are still synchronized with the state transitions.
u" n
"■ — n"
y | y
Uj 1 1 1 1 1 1 1 1 1 1 1 1 1 1 j i j | [ lyiTTTJTPT
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Reference
□
Different Pulse Mode Settings on a Keyboard Sensor
Sensors
Before activating any pulse mode in the Sensor, try first without, this can save much performance, this is
especially important with the Always Sensor. If you still need a pulse mode, think if you can raise the f:
(frequency) setting, this can also save much performance.
If none of the mode buttons are activated the Always Sensor fires exactly one time. This is very useful for
initializing stuff at the start of a game.
Lvl button: This button has only an effect when entering a state (when the state to which the sensor is
connected is being activated due to a state actuator). Normally, a sensor generates an event (activates the
controller) only when there is a transition in its internal state. When the Lvl button is selected, the sensor will
always generate an initial event, whether positive or negative, based on the current sensor state. Example: you
have a keyboard sensor that controls a motion actuator; you want the motion actuator to be immediately
activated even if the key is already pressed when entering the state, so select the Lvl button.
Limitation: for the time being, this works reliably only if the sensor is connected to a single state. In a future
version, it will work even if the sensor is used by multiple states.
Examples:
• PulseModesDiagramm.blend (visualizes the Pulses and their values)
• MoveCertainDist.blend (different uses of Pulse-Modes with the Motion Actuator)
Common Sensor Python Functions
returns
Function
Explanation
integer
getFrequency()
The frequency for mode sensors
bool
getlnvert()
True if this sensor activates on negative events.
bool
getUseNegMode()
True if the sensor is in negative mode.
bool
getUsePosMode()
True if the sensor is in positive mode.
bool
isPositiveO
True if this sensor brick has been activated.
setFrequency(freq)
Sets the frequency for mode sensors.
setlnvert(invert)
Sets if this sensor activates on positive (true) or negative
events.
setUseNegMode()
Sets negative mode.
setUsePosMode()
Sets positive mode.
bool
getLevel()
Returns whether this sensor is a level detector or a edge
detector.
bool
isPositive()
True if this sensor brick is in a positive state.
bool
isTriggered()
True if this sensor brick has triggered the current
controller.
reset()
Reset sensor internal state, effect depends on the type of
sensor and settings.
setLevel(level)
Set whether to detect level or edge transition when
entering a state.
bool
isAQ
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Reference
Sensors
Allows to check if a python object is of a certain type. For
example, if you get an object from the scene's object list,
you can check if this object is of type lamp: if
ob.isA("KX_LightObject"): ...
All Sensors provide these functions.
Delay Sensor
X I D
elay
sensed
' f:
Delay
Lvl In
DurQ REP
□
The Delay sensor generates positive and negative triggers at precise time, expressed in number of frames. The
delay parameter defines the length of the initial OFF period. A positive trigger is generated at the end of this
period. The duration parameter defines the length of the ON period following the OFF period. There is a
negative trigger at the end of the ON period. If duration is 0, the sensor stays ON and there is no negative
trigger. The sensor runs the OFF-ON cycle once unless the repeat option is set, then the OFF-ON cycle
repeats indefinitely (or the OFF cycle if duration is 0).
Delay Sensor Python Functions
returns
Function
setDelay(delay)
Set the initial delay (in frames) before the positive trigger.
setDuration(duration)
Set the duration (in frames) of the ON pulse after initial delay and the
generation of the positive trigger.
setRepeat(repeat)
Set the sensors repeat mode.
integer
getDelayO
Return the delay parameter value.
integer
getDurationO
Return the duration parameter value
bool
getRepeatQ
Return the repeat parameter value
Keyboard Sensor
X Keyboard
sensor2
at h
ail <*
f:
Lvl Inv |
Key
All keys
Hold
LogTo
ggle:
Target
□
The Keyboard Sensor is one of the most often used Sensors because it provides the interface between Blender
and the user.
The mode buttons are common for every Sensor so they have the same functionality as described for the
Always Sensor.
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Reference
Sensors
By activating the "All keys" Button, the Sensor will react to every key. In the "Hold" fields you can put in
modifier keys, which need to be held while pressing the main key.
The Keyboard Sensor can be used for simple text input. To do so, fill in the Property which should hold the
typed text (you can use Backspace to delete chars) into the "Target:" field. The input will be active as long the
Property in "LogToggle:" is "TRUE".
Python methods:
Keyboard Sensor Python Functions
returns
Function
integer
getKeyO
Returns the key code
this sensor is looking
for.
setKey(keycode)
Set the key this sensor
should listen for.
list of kev status, kevcode.
status
getPressedKeys()
Get a list of keys that
have either been
pressed, or just
released this frame
(when the Sensor is
triggered)
list of kev status, kevcode.
status
getCurrentlyPressedKeysQ
Get a list of currently
pressed keys that have
either been pressed, or
just released. With this
function you will get
all pressed keys even
if the Sensor is not
triggered anymore.
Import the Game Keys module (see #GameKeys Module ) to have symbolic names for the keys.
Mouse Sensor
Mouse
sensorj
« f:
Lvl | Inv I
Left button
□
Currently, the Sensor is able to watch for mouse clicks, mouse movement or a mouse over. To get the position
of the mouse cursor as well you need to use a Python- script.
To get the coordinates of the mouse it is necessary to use Python, see the examples.
Python methods:
Common Mouse Sensor
Python Functions
returns
Function
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Reference
Sensors
integer
getXPosition( )
Gets the mouse's X-position
integer
getYPosition( )
Gets the mouse's Y-position
Use the Menu Button to choose between the Mouse Sensor types:
Type
Mouse over any
Mouse over
Jl
:
■
Movement
Wheel Down
=:
Wheel Up
Right button
J
Middle button
-
1
Left button
Left button
□
Left/Middle/Right Button
The sensor gives out an event when the correlate mouse button is pressed.
Wheel up/down
The sensor gives an event when the mouse wheel is moved up or down.
Movement
The sensor sends out an event when the mouse is moved.
The following to mouse over modes are working as follow: a ray is fired from the mouse pointer into the
scene (see examples section below on how to make the mouse pointer visible in a game). The results of the
ray to object collision can be used in several ways, this reflects in the python functions for the mouse over
modes.
Mouse over
The Sensor sends an event when the mouse pointer is over the object which carries the
Sensor. To make mouse over works as expected, ensure to start the game in a Camera view!
Mouse over any
The Sensor sends an event when the mouse pointer is over any object (with collision faces).
To make mouse over any works as expected, ensure to start the game in a Camera view !
Mouse Over Any Sensor Python Functions
returns
Function
list [x, y, z]
getHitNormalO
Returns the normal of the detected face
KX_GameObject
getHitObject()
Returns game object the mouse is over
list [x, y, z]
getHitPositionO
Position in space where the ray hits the object
list [x, y, z]
getRayDirection()
Where the ray points to
list [x, y, z]
getRayTarget()
Returns the end point of the sensor ray.
list [x, y, z]
getRaySourceQ
Returns the start point of the sensor ray.
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Reference
Sensors
Examples:
• Blends /Reference/MouseOverAdd. blend (Trackball View, Blender style, uses
MMB)</code>
• Blends /Re ference/ShowMouse .blend (making the mouse pointer visible)</code>
• Blends /Reference/MouseOverAdd. blend (adding objects at the mouse cursor)</code>
• Blends /Reference/GetHitNormal .blend (use of getHitNormal())</code>
Touch Sensor
JC| Touch
' l|sensor4
"■ „.
en
Lvl
Inv |
□
The Touch Sensor gives an event when the object it is assigned to, touches a material. If you enter a material
name into the "MA:" text field it only reacts to this material otherwise it reacts to all touches.
The Touch Sensor inherits from the Collision Sensor, so it provides the same methods, hence the method
names. See also #Collision Sensor.
Touch Sensor Python Functions
returns
Function
Explanation
setProperty(name)
Argument is a string containing the property or material
name to collide with.
string
getProperty()
Returns the property or material to collide with.
KX_GameObject
getHitObjectO
Returns the last object hit by this touch sensor.
list
[KX_GameObject]
getHitObjectListO
Returns a list of all objects hit in the last frame.
bool
getTouchMaterial()
Returns true if this sensor looks for a specific material, false
if it looks for a specific property.
setTouchMaterial(flag)
Set flag to true to switch on positive pulse mode, false to
switch off positive pulse mode.
Collision Sensor
□
The Collision Sensor is a general Sensor used to detect contact between objects. Besides reacting to materials
it is also capable of detecting Properties of an object. Therefore you can switch the input field from Material
to Property by clicking on the "M/P" button.
Collision Sensor Python Functions
returns
Function
Explanation
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Reference
Sensors
setProperty(name)
Argument is a string containing the property or material
name to collide with.
string
getProperty()
Returns the property or material to collide with.
KX_GameObject
getHitObject()
Returns the last object hit by this touch sensor.
list
[KX_GameObject]
getHitObjectListO
Returns a list of all objects hit in the last frame.
bool
getTouchMaterial()
Returns true if this sensor looks for a specific material, false
if it looks for a specific property.
setTouchMaterial(flag)
Set flag to true to switch on positive pulse mode, false to
switch off positive pulse mode.
Near Sensor
The near sensor reacts to actors near the object with the sensor.
X | Near
sensorB
at
IS!
4
f:
Lvl
Inv
[Property:
1 Dist 1 .00
»| 4
Reset 2.00
H
.J
□
The near sensor only senses objects of the type "Actor" (a dynamic object is also an actor).
If the "Property:" field is empty, the near sensor reacts to all actors in its range. If filled with a property name,
the sensor only reacts to actors carrying a property with that name.
You can set the spherical range of the near sensor with the "Dist" Number Button. The "Reset" value defines
at what distance the near sensor is reset again.
The Near Sensor is a special case of a touch sensor, see #Touch Sensor for the Python methods and functions.
Radar Sensor
□
The Radar Sensor acts like a real radar.
It looks for an object along the axis indicated with the axis pop up
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Reference
Sensors
□
If a property name is entered into the "Prop:" field, it only reacts to objects with this property.
In the "Ang:" field you can enter an opening angle for the radar. This equals the angle of view for a camera.
The "Dist:" setting determines how far the Radar Sensor can see.
Objects can't block the line of sight for the Radar Sensor. This is different for the Ray Sensor (see #Rav
Sensor) . You can combine them for making a radar that is not able to look through walls.
Radar sensor is a near sensor with a conical sensor object. Please look at #Near Sensor for the common
Python methods.
Radar Sensor Python Functions
returns
Function
Explanation
list [x, y,
z]
getConeOrigin()
Returns the origin of the cone with
which to test.
list [x, y,
z]
getConeTarget() IReturns the center of the bottom face of
the cone with which to test.
float
getConeHeightQ
Returns the height of the cone with
which to test.
Examples:
• RadarSensor.blend
Property Sensor
□
The Property Sensor senses Properties attached to the object carrying the Property Sensor.
cTjpe
t Changed
Interval
I Not Equal
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Reference
□
You can change the type with the pop up menu to Equal, Not Equal, Interval and Changed.
Sensors
The "Equal" type Property Sensor checks for equality of the property given in the "Prop:" field and the value
in "Value:". If the condition is true, it fires events according to the pulse mode settings.
The "Not Equal" Property Sensor checks for inequality and then fires its events.
The "Interval" type property sensor fires its event if the value of property is inside the interval defined by
"Min:" and "Max:". This sensor type is especially helpful for checking float values, for which you can't
depend on to reach a value exactly. This is most common with the "Timer" Property.
The "Changed" Property Sensor gives out events every time a Property is changed. This can, for example,
happen through a Property Actuator, a Python script or an Expression.
Property Sensor Python Functions
returns
Function
Explanation
getType()
Gets when to activate this sensor.
setType(checktype)
Set the type of check to perform.
string
getPropertyO
Return the property with which the sensor operates.
setProperty(name)
Sets the property with which to operate.
string
getValue()
Return the value with which the sensor compares to the value of the
property.
setValue(value)
Set the value with which the sensor operates.
Random Sensor
Random
sensor9
Lvl
IQ
* ! 1 1
8*8
f:
1 mv !
Seed:
-J
□
The Random Sensor fires a pulse randomly according to the pulse settings (50/50 pick). The Random is a so
called "pseudo random", that means with the same seed the same sequence of numbers will be generated. This
can be used to achieve "random" behavior that is the same on every game start. For more complex random
functions see #Random Actuator.
With a seed of zero the Random Sensor works like an Always Sensor, which means it fires a pulse every time.
Property Sensor Python Functions
returns
Function
Explanation
setSeed(seed)
Sets the seed of the random number generator.
integer
getSeed()
Returns the initial seed of the generator.
bool
getLastDrawQ
Returns the last random number generated.
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Reference
Ray Sensor
Sensors
It B
i i e
f:
"1
Lvl
Inv J
M/P
Property:
□
The Ray Sensor casts a ray for the distance set into the Number Button "Range". If the ray hits an object with
the right Property or the right Material the Sensor fires its event.
Other objects block the ray, so that it can't see through walls. See also #Radar Sensor
Without a material or property name filled in, the Ray Sensor reacts to all objects.
Ray Sensor Python Functions
returns
Function
Explanation
KX_GameObject
getHitObject() Returns the game object
that was hit by this ray.
list [x, y, z]
getHitPositionO
Returns the position (in world
coordinates) where the object was hit by
this ray.
list [nx, ny, nz]
getHitNormal()
Returns the normal (in world
coordinates) of the object at the location
where the object was hit by this ray.
list [dx, dy, dz]
getRayDirection()
Returns the direction from the ray (in
world coordinates)
Message Sensor
□
The Message Sensor fires its event when a Message arrives. The "Subject:" field can be used to filter
messages matching the given subject.
Message Sensor Python Functions
returns
Function
Explanation
setSubjectFilterText(subject)
Change the message subject text that this sensor is listening to.
integer
getFrameMessageCountO
Get the number of messages received since the last frame.
list
getBodies()
Gets the list of message bodies.
string
getSubjectQ
Gets the message subject this sensor is listening for from the
Subject: field.
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Reference
Sensors
list
getSubjectsQ
Gets the list of message subjects received.
See in section #Message Body on how to get the message body.
Joystick Sensor
□
With the joystick sensor you can access joysticks, game pads and other gear connected to the computer. With
logic bricks it is only possible to use button and to check if a joystick axis is moved a certain amount. To get
the values of analog devices it is necessary to use a Python script, see the examples below.
With the type menu of the joystick sensor you can choose what the sensor sould sense.
Common for all Joystick Sensor types is "Index:", which tells Blender which joystick to use. The "All" button
selects that all events for this type should trigger the sensor, especially usefull for Python scripts.
□
Button The number button "Number: 0" selects the joystick button to use.
□
Axis With "Number: 1" you choose which axis pair to use. With the menu right to the "Number: 1" Button
you choose in which direction the stick needs to be moved for the sensor to fire an event. With "Threshold: 0"
you can choose a value how much the stick needs to be moved to let the sensor fire. This is mostly used if a
analog stick is used.
□
Hat Some joysticks and game pads have a hat-controller, mostly used to change the view direction. With the
"Number: 1" button you choose which head-controller to use. Hat-controllers can sense usually 8 directions,
up, up+right, right, right+down, etc. The "Direction:" field gives the direction in a binary manner:
Direction
Value
up
1
right
2
down
4
left
8
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Reference
Sensors
If you like to check for up and right you simply add the values, 1+2=3. Of course normally you can't press up
and down at the same time on conventional sticks, but of course this way we are very flexible and have a 4 bit
digital input we could use also for other things (robotic experiments, other types of input devices...)-
Joystick Sensor Python Functions
returns
Function
Explanation
list
getAxis
Returns the current axis this sensor reacts to.
list
getAxisValue
Returns a list of the values for the current state of each axis.
integer
getButton
Returns the current button this sensor is checking.
list
getButtonValue
Returns a list containing the indicies of the current pressed state of each button.
list
getHat
Returns the current direction of the hat.
integer
getlndex
Returns the joystick index to use.
integer
getNumAxes
Returns the number of axes .
integer
getNumButtons
Returns the number of buttons .
integer
getNumHats
Returns the number of hats .
integer
getThreshold
Returns the threshold of the axis.
bool
isConnected
Returns True if a joystick is connected at this joysticks index.
setAxis
Sets the current axis this sensor reacts to.
setButton
Sets the button the sensor reacts to.
setHat
Sets the hat the sensor reacts to.
setlndex
Sets the joystick index to use.
Examples: - Analoglnput.blend (get analog input from a joystick)
Actuator Sensor
□
The actuator sensor detects when certain actuator on the same object is triggered, useful for reducing the
number of controllers and wires because you don't need to pass this information with properties anymore.
The sensor generates a positive when the corresponding sensor is activated and a negative when it is
deactivated (the contrary if the Inv option is selected).
Actuator Sensor Python Functions
returns
Function
Explanation
string
getActuatorO
Return the Actuator with which the sensor operates.
setActuator(name)
Sets the Actuator with which to operate.
Notes:
Actuators are disabled at the start of the game; if you want to detect the On-Off transition of an
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Reference
Controllers
actuator after it has been activated at least once, unselect the Lvl and Inv options and use a NAND
controller.
Some actuators deactivates themselves immediately after being activated. The sensor detects this
situation as an On-Off transition.
Examples:
• See Pinnball tutorial (detection of an complete played Ipo)
• This Actuator is also very to detect the loss of contact of the distance Constraint Actuator
Controllers
□
Controllers act as the brain for your game logic. This reaches from very simple decisions like connecting two
or more inputs, simple expressions, to complex Python scripts which can carry artificial intelligence.
Common Controller Python Functions
returns
Function
Explanation
list [SCAJSensor]
getSensors()
Gets a list of all
sensors attached
to this
controller.
SCAJSensor
getSensor(name)
Gets the named
linked sensor.
list [SCA_IActuator]
getActuators()
Gets a list of all
actuators linked
to this
controller.
SCAJActuator
getActuator(name)
Gets the named
and linked
actuator.
integer
getExecutePriorityO
Returns the
priority for this
actuator
setExecutePriority(priority)
Sets the priority
for this actuator
string
getName
Get the given
name
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Reference
Simple Logical Controllers
KX_GameObject
getOwner()
Gets the owner
of the
Controller
string
getScript()
Get the name of
the Python
script
setScript(scriptname)
Set the name of
the Python
script
integer
getState()
Get the current
state of the
Controller
bool
isA() allows to check if a python object is of a certain type. For
example, if you get an object from the scene's object list, you can
check if this object is of type lamp: if ob.isA("KX_LightObject"):
Simple Logical Controllers
X AND
true.
_ X I OR
inputs is true.
■ cont
® The AND controller only passes an event if all inputs are
cont
1 Q
*• The OR controller passes an event if any number of the
output is true if any of the input is false.
X NOR
cont
output is false if any of the input is true.
X XOR
cont
if and only if one input is true and all the other inputs are false.
*• The NAND controller is an inverted AND controller: the
** The NOR controller is an inverted OR controller: the
** The XOR controller is an exclusive OR: the output is true
X XNOR
cont
® The XNOR controller is an inverted XOR: the output is
false if and only if one input is false and all the other inputs are true.
The NAND, NOR and XNOR controllers are very useful to create complementary outputs to start and stop
actuators synchronously.
Expression Controller
> | Expression
cont
□
Exp:
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Reference Expression Controller
□
With the Expression Controller you can create slightly complex game logic with a single line of "code". You
can access the output of sensors attached to the controller and access the properties of the object.
The expression mechanism prints out errors to the console, so have a look there if anything fails.
Expressions
Expressions can be used in the Expression Controller and the Property Actuator.
Table: Valid expressions
Expression type
Example
Integer numbers
15
Float number
12.23224
Booleans
TRUE, FALSE
Strings
"I am a string!"
Properties
propname
Sensornames
sensorname (as named in the sensor LogicBrick)
Table: Arithmetic expressions
Expression
Example
EXPR1 + EXPR2
Addition, 12+3,
propname+21
EXPR1 - EXPR2
Subtraction, 12-3,
propname-21
EXPR1 * EXPR2
Multiplication, 12*3,
propname*21
EXPR1 / EXPR2
Division, 12/3, propname/21
EXPR1 > EXPR2
EXPR1 greater then EXPR2
EXPR1 >= EXPR2
EXPR1 greater or equal
EXPR2
EXPR1 < EXPR2
EXPR1 less than EXPR2
Table 26-3. Boolean operations
Operation
Example
NOT EXPR
Not EXPR
EXPR1 OR EXPR2
logical OR
EXPR1 AND EXPR2
logical AND
EXPR1 == EXPR2
EXPR1 equals
EXPR2
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Reference
Conditional statement: IF( Test, ValueTrue,
ValueFalse )
Python Controller
Table 26-4. Expression examples
Expression
Result
Explanation
12+12
24
Addition
property=="Carsten"
TRUE or FALSE
String comparison between a Property and a string
"Erwin'V'Carsten"
FALSE
A string compare is done
Python Controller
Python
i"
cont
. SCripJ:
«>
□
The Python controller is the most powerful controller in game engine. You can attach a Python script to it,
which allows you to control your GameObjects, ranging from simple movement up to complex game-play and
artificial intelligence.
Enter the name of the script you want to attach to the Python Controller into the "Script:" field. The script
needs to exist in the file or Blender will ignore the name you type.
Remember that Blender treats names as case sensitive! So the script "player" is not the same as "Player".
Python for the game engine is covered in #Game engine Python
Python Controller Functions
returns
Function
Explanation
string
getScript()
Gets the Python script this controller executes.
setScript(script)
Sets the Python script this controller executes.
State System
States are a way to achieve complex logics without cluttering your Logic Buttons and having to redo already
existing Logic Bricks. States are a group of Logic Bricks which get executed at a certain time or state (hence
the name) of the game.
Imagine a character wandering around. There may be different materials for the ground (e.g. ice and sand), a
different control method in water or air, etc. Without states you would now start to use Properties,
Property-Sensors and Actuators to control what state the actor has. With the state system probably only one
LogicBrick changes the state and you are done.
State internals (by Benoit Bolsee)
The state system is object based. The current state mask is stored in the object as a 32 bit value; each bit set in
the mask is an active state. The controllers have a state mask too, but only one bit can be set: a controller
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Reference State System
belongs to a single state. The game engine will only execute controllers that belong to active states. Sensors
and actuators don't have a state mask but are effectively attached to states via their links to the controllers.
Sensors and actuators can be connected to more than one state. When a controller becomes inactive because of
a state change, its links to sensors and actuators are temporarily broken (until the state becomes active again).
If an actuator gets isolated, i.e all the links to controllers are broken, it is automatically disabled. If a sensor
gets isolated, the game engine will stop calling it to save CPU power. It will also reset the sensor internal state
so that it can react as if the game just started when it gets reconnected to an active controller. For example, an
Always sensor in no mode that is connected to a single state (i.e connected to one or more controllers of a
single state) will generate a event each time the state becomes active. This feature is not available on all
sensors, see the notes below.
State GUI
This system system is fully configurable through the GUI: the object state mask is visible under the object bar
in the controller's colum as an array of buttons just like the 3D view layer mask. Click on a state bit to only
display the controllers of that state. You can select more than one state with SHIFT-LMB. The "All" button
sets all the bits so that you can see all the controllers of the object. The "Ini" button sets the state mask back to
the objects default state. You can change the default state of objects by first selecting the desired state mask
and storing using the menu under the "State" button.
□
If you define a default state mask, it will be loaded into the object state make when you load the blend file or
when you run the game under the Blenderplayer. However, when you run the game with Blender, the current
selected state mask will be used as the startup state for the object. This allows you to test specific state during
the game design.
The controller displays the state they belong to with a new button in the controller header. When you add a
new controller, it is added by default in the lowest enabled state. You can change the controller state by
clicking on the button and selecting another state. If more than one state is enabled in the object state mask,
controllers are grouped by state for more readability.
The new "Sta" button in the sensor and actuator column header allows you to display only the sensors and
actuators that are linked to visible controllers.
A new state actuator is available to modify the state during the game. It defines a bit mask and the operation to
apply on the current object state mask:
Cpy: the bit mask is copied to the object state mask.
Add: the bits that set in the bit mask will be turned on in the object state mask.
Sub: the bits that set in the bit mask will be turned off in the object state mask.
Inv: the bits that set in the bit mask will be inverted in the object state mask.
Things to note:
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Reference
State GUI
• Although states have no name, a simply convention consists in using the name of the first controller
of the state as the state name. The GUI will support that convention by displaying as a hint the name
of the first controller of the state when you move the mouse over a state bit of the object state mask or
of the state actuator bit mask.
• Each object has a state mask and each object can have a state engine but if several objects are part of a
logical group, it is recommended to put the state engine only in the main object and to link the
controllers of that object to the sensors and actuators of the different objects.
• When loading an old blend file, the state mask of all objects and controllers are initialized to 1 so that
all the controllers belong to this single state. This ensures backward compatibility with existing
games.
• When the state actuator is activated at the same time as other actuators, these actuators are guaranteed
to execute before being eventually disabled due to the state change. This is useful for example to send
a message or update a property at the time of changing the state.
• Sensors that depend on underlying resource won't reset fully when they are isolated. By the time they
are activated again, they will behave as follow: Keyboard sensor: keys already pressed won't be
detected. The keyboard sensor is only sensitive to new key press. Collision sensor: objects already
colliding won't be detected. Only new collisions are detected. Near and radar sensor: same as
collision sensor.
Actuators
Actuators are the executing Logic Bricks. They can be compared with muscles or glands in a life form.
Depending on the type or purpose of an Actuator, an Actuator can act differently on a pulse. Some inputs are
more like keys (the get released when no pulse arrives) some act more like a switch (needs to be switched of
by a pulse carrying a negative value). This is especially important for the Motion Actuator.
Common Actuator Python Functions
returns
Function
Explanation
integer
getExecutePriority()
Returns the priority for this actuator
setExecutePriority(priority)
Sets the priority for this actuator
string
getName()
Get the given name
KX_GameObject
getOwner()
None
bool
isA()
allows to check if a python object is of a
certain type. For example, if you get an
object from the scene's object list, you
can check if this object is of type lamp:
if ob.isA("KX_LightObject"): ...
(Shape) Action Actuator
The Shape Action Actuator will play Actions or Shape Key animations in the game engine. If you add it to a
mesh, it will add a Shape Action Actuator, if added to an Armature it will be an Action Actuator. Have a look
at the examples below and the Character Animation tutorial.
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Reference
(Shape) Action Actuator
y»)
X Shape Action
actZ
s
1"
!
J Ptay
AC:
BH
1 < 51a:
* 1 4
End:
Blendin;
Priority
i JFrameProp:
HH
□
Fill in the start and end frame of your action into the "Sta:" and "End:" fields.
Action play modes
Play: Plays the Action from "Sta" to "End" at every positive pulse the Actuator gets. Other pulses while
playing are discarded.
Flipper: Plays the Action from "Sta" to "End" on activation. When the activation ends it plays backwards
from the current position. When a new activation reaches the Actuator the Action will be played from the
current position onwards.
Loop Stop: Plays the Action in a loop as long as the pulse is positive. It stops at the current position when the
pulse turns negative.
Loop End: This plays the Action repeatedly as long as there is a positive pulse. When the pulse stops it
continues to play the Action to the end and then stops.
Property: Plays the Action for exactly the frame indicated in the property entered in the field "Prop:".
Enter the name of your (Shape) Action into the field "AC:". Blender will blank the input if the entered name
does not exist.
If you switch states the "Continue" -button becomes important. In case that the "Continue" -button is pressed,
upon deactivation of the Actuator, the last played frame of the action will be stored and restored when the
Actuator is enabled (because of a state switch) again.
In case you have more than on Action on your Object, "Blendin:" allows you to blend between the Actions.
"Blendin:" is measured in numbers of frames.
Actions with lower "Priority:" will override Actions with higher priority. Keep in mind that the overriding
Actions need to be lower in the Actuators stack.
Enter a Property name into the "FrameProp:" filed to get the actual frame number of the played action. This is
very handy to synchronize the game with specific actions.
Action Actuator Python Functions
returns
Function
Explanation
setAction(action,
reset=True)
Sets the current action
setStart(start)
Specifies the starting frame of the animation
setEnd(end)
Specifies the ending frame of the animation
setB lendin(blendin)
Specifies the number of frames of animation to generate when
making transitions between actions
setPriority(priority)
Sets the priority of this actuator
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Reference
Motion Actuator
setFrame(frame)
Sets the current frame for the animation
setProperty(prop)
Sets the property to be used in FromProp playback mode
setBlendtime(blendtime)
Sets the internal frame timer
setType(mode)
Sets the operation mode of the actuator
setContinue(cont)
Set the actions continue option True or False
integer
getType()
Returns the operation mode of the actuator
boot
getContinue()
When True, the action will always play from where last left off,
otherwise negative events to this actuator will reset it to its start
frame
string
getAction()
returns the name of the action associated with this actuator
float
getStart()
Returns the starting frame of the action
float
getEnd()
Returns the last frame of the action
float
getBlendin()
Returns the number of interpolation animation frames to be
generated when this actuator is triggered
float
getFrame()
Returns the current frame number
string
getPropertyO
Returns the name of the property to be used in FromProp mode.
setChannel(channel, matrix,
mode=False)
Sets the channel to use
setAction(action,
reset=True)
Sets the current action, action (string): The name of the action to set
as the current action, reset: Optional parameter indicating whether to
reset the blend timer or not. A value of 1 indicates that the timer
should be reset. A value of will leave it unchanged. If reset is not
specified, the timer will be reset.
setStart(start)
Specifies the starling frame of the animation. Parameters: start
(float) the starting frame of the animation
Examples:
ShapeAction.blend (Shape and Armature Action playing in the game engine)
Motion Actuator
The motion actuator is meant to move objects. Depending if you have a non-dynamic (so not evaluated by the
physic engine) or dynamic object (see Doc:Reference l) it changes its appearence a bit. So for non-dynamic
objects the Simple Motion Actuator would look like:
0.00 0.00
Q.QO O.OO
1.00
100
□
Because we operate in a 3D environment all parameters are for all three axis, so the numbers below are meant
from left to right as X, Y and Z value of a parameter.
Loc: X, Y and Z value the object should be moved upon activation of the Actuator.
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Reference
Motion Actuator
Rot: Rotation around X, Y and Z axis when the Actuator is activated. Normally you can look at this value as
rotation speed. However if you need to rotate a certain amount of degrees you can use this formula to
calculate the value for the Rot-parameter: Rot = Degrees / 50
With activated (default) "L"-buttons (L for local) all rotations and movements will be along the objects axes.
With a deactivated "L"-button the movement or rotation will be along the world coordinates.
Notes:
• The Motion Actuator needs a negative event to deactivate, see "examples/MoveCertainDist.blend"
For dynamic Objects there are much more options:
X| Motion i ad
Simple motion
Loc ' 0.00
0.00 "
o.oo
Rot < 0.00 ►
« 0.00 ►
< 0.00 ►
Force < 0.00 ►
< 0.00 ►
« O.0Q ►
8
Torque 0,00 -
« 0.00 *
< 0.00 »
LinV < 0.00 ►
0.00
« O.0Q "
LJ add |
AngV < 0.00 >
0.00
0.00
L
Damp
□
Loc: X, Y and Z value the object should be moved upon activation of the Actuator.
Rot: Rotation around X, Y and Z axis when the Actuator is activated. Normally you can look at this value as
rotation speed. However if you need to rotate a certain amount of degrees you can use this formula to
calculate the value for the Rot-parameter: Rot = Degrees / 50
The movement and orientation of dynamic Objects is usually evaluated by the physics engine to simulate
natural behaviors of the objects, e.g. falling and colliding with other objects. Using Loc/Rot for dynamic
objects is not recommended unless you know what you are doing or you want to achieve a special effect.
Force: Dynamic objects have a mass, and you need a force to move them. This force can be set here for X, Y
and Z axes.
Torque: Same as for Force but here a force to rotate the object
LinV: Sets a linear velocity of the object. This can be used to set a starting speed of an object, but it should
not be used to actually move the object. When the "Add"-button is pressed the velocity will be added to the
existing object velocity
AngV: Same as Linv but for rotational speed
Damp: Damp works only for LinV and AngV (linear and angular Velocity). It defines the time constant, in
frames, to get to the specified velocity.
With activated (default for Loc/Rot/Force/Torque) "L"-buttons (L for local) all rotations and movements will
be along the objects axes. With a deactivated "L"-button the movement or rotation will be along the world
coordinates.
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Reference
Motion Actuator
To avoid problems with objects getting faster and faster, or to allow more control over your game-physics
there is another type of Motion Actuator, the Servo Control Actuator. You choose this type with the "Motion
Type"-menu:
Motion actl
Servo Contra!
□
This variant of the motion actuator allows to control speed with force. The control is technically of the type
"PID" (Propotional, Integral, Derivate): the force is automatically adapted to achieve the target speed. All the
parameters of the Servo Actuator are configurable. The result is a great variety of motion style: anisotropic
friction, flying, sliding, pseudo Dloc, etc. This actuator should be used in preference to Dloc and LinV as it
produces more fluid movements, avoids the collision problems with Dloc and interacts correctly with gravity
unlike linV.
LinV : target speed as (X,Y,Z) vector in local or world coordinates (mostly useful in local coordinates).
Limit: the force can be limited along each axis (in the same coordinates of LinV). No limitation means that
the force will grow as large as necessary to achieve the target speed along that axis. Set a max value to limit
the acceleration along an axis (slow start) and set a min value (negative) to limit the brake force.
P: Proportional coefficient of servo controller, don't set directly unless you know what you're doing.
I: Integral coefficient of servo controller. Use low value (<0.1) for slow reaction (sliding), high values (>0.5)
for hard control. The P coefficient will be automatically set to 60 times the I coefficient (a reasonable value).
D: Derivate coefficient. Leave to unless you know what you're doing. High values create instability.
Notes:
The servo motion actuator applies forces, it is therefore not compatible with other actuators that sets the force
too, i.e a simple motion force actuator or another servo motion. Although it is possible to combine two servo
motion actuators that works on different axis.
This actuator is compatible with simple Drot motion actuator but not with LinV and Dloc motion.
This actuator works perfectly in zero friction environment: the PID controller will simulate friction by
applying force as needed.
(0,0,0) is a valid target speed.
Motion Actuator Python Functions
returns
Function
Explanation
list [x,y,z,local]
getAngularVelocity
Gets the angular Velocity (AngV) set in the
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Reference
Constraint Actuator
Actuator
list [x,y,z,local]
getDLoc
Gets the Loc set in the Actuator
list [x,y,z,local]
getDRot
Gets the Rot set in the Actuator
integer
getDamping
Gets the Damp set in the Actuator
list [x,y,z,local]
getForce
Gets the Force set in the Actuator
list [min,max,active]
getForceLimitX
Gets the force limit X as set in the Actuator
(Servo Control)
list [min,max,active]
getForceLimitY
Gets the force limit Y as set in the Actuator
(Servo Control)
list [min,max,active]
getForceLimitZ
Gets the force limit Z as set in the Actuator
(Servo Control)
setForceLimitX
Sets the force limit for the x-axis
setForceLimitY
Sets the force limit for the y-axis
setForceLimitZ
Sets the force limit for the z-axis
list [x,y,z,local]
getLinearVelocity
Gets the linear velocity set in the Actuator
list [x,y,z,local]
getTorque
Gets the torque set in the Actuator
setAngularVelocity()
Sets the torque value
list [x,y,z]
setDLoc(x,y,z,local)
Set the values for the DLoc row, use local=0
to move along global axes
list [x,y,z]
setDRot(x,y,z,local)
Set the values for the DRot row, use local=0
to rotate around global axes
setDamping(damping)
Damping for the HnV/linRot
setForce(x,y,z,local)
Set the values for the Force row, use local=0
to move along global axes
setLinearVelocity(x,y,z,local)
Set the values for the linV row, use local=0 to
move along global axes
setTorque(x,y,z,local)
Set the values for the Torque row, use
local=0 to rotate around global axes
Constraint Actuator
The Constraint Actuator offers different ways to constraint or inhibit a movement or degree of freedom. Use
the "Constraint Type"-menu to choose between Location, Orientation and Distance.
€>
X j Comlramt
ansa
3QE
LocaJiBn
»|
— J
J_jJamp__0 Win
[ None
0.00
Max
0.00
□
: Canstrssm type
1 Or isn taken
_ Distant e
□
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Reference
Constraint Actuator
Location
With the Constraint Actuator of the type "Location" you can constraint the location of an object in the
3d-space.
Limit
I Loc Z
*Loc V
*
None
Min
□
First choose a axis at which you want to limit the movement. If you need to constraint an object on more axes,
use more Constraint Actuators.
With the values under "Min" and "Max" you adjust the limits of the movement. The values are in Blender
units.
"damp" controls how fast/hard (low values) or slow/soft (high values) the Actuator reacts on a position change
of the object.
Notes:
for dynamic objects this Controller is of limited use because it will not define a hard border, instead have a
look at #Reference
for dynamic objects try to use the Servo-Control Motion Actuator
Examples:
• See the "Flying Buddha" demo (Buddha main character)
Distance
[Icheck Change!] This variant of the constraint actuator allows to set the distance and orientation relative to a
surface. The controller uses a ray to detect the surface (or any object) and adapt the distance and orientation
parallel to the surface.
S
□
X | Constraint i | act3
Distance
= 1
damp Range
Dist
None COO N |
r*P Property:
PER time
rOtDSmp
Damp: Time constant (in numbers of frames) of distance and orientation control.
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Reference Constraint Actuator
Dist: Select to enable distance control and set target distance. The object will be position at the given distance
of surface along the ray direction.
□
Direction: chose a local axis as the ray direction.
Range: length of ray. Object within this distance will be detected.
N: Select to enable orientation control. The actuator will change the orientation and the location of the object
so that it is parallel to the surface at the vertical of the point of contact of the ray.
M/P: Select to enable material detection. Default is property detection.
Property/Material: name of property /material that the target of ray must have to be detected. If not set,
property/ material filter is disabled and any colliding object within range will be detected.
PER: Select to enable persistent operation. Normally the actuator disables itself automatically if the ray does
not reach a valid target.
time: Maximum activation time of actuator. Zero means unlimited, values above zero meaning number of
frames before automatic deactivation.
rotDamp: Time constant (in numbers of frame) of orientation control. Zero: use Damp parameter. Above
zero: use a different time constant for orientation.
Notes:
• If neither N nor Dist options are set, the actuator does not change the position and orientation of the
object; it works as a ray sensor.
• The ray has no "X-ray" capability: if the first object hit does not have the required property/material,
it returns no hit and the actuator disables itself unless PER option is enabled.
• This actuator changes the position and orientation but not the speed of the object. This has an
important implication in a gravity environment: the gravity will cause the speed to increase although
the object seems to stay still (it is repositioned at each frame). The gravity must be compensated in
one way or another, the new servo control motion actuator is the simplest way: set the target speed
along the ray axis to and the servo control will automatically compensate the gravity.
• This actuator changes the orientation of the object and will conflict with Drot motion unless it is
placed BEFORE the Drot motion actuator (the order of actuator is important)
• All parameters are accessible through Python.
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Reference
Orientation
Constraint Actuator
This variant of the constraint actuator allows to align an object axis along a global direction.
X Constrain! ; act3
Orientation
damp OX V Z
None ' O.OG ■"• < O.OO ► < 0,00 >
< timeO ► minO.O
maxO.G ;
3
□
Damp: Time constant (in numbers of frames) of orientation control.
X,Y,Z: Global coordinates of reference direction.
time: Maximum activation time of actuator. Zero means unlimited, values above zero meaning number of
frames before automatic deactivation.
Direction: chose a local axis as the ray direction.
Direction
□
Notes:
• (X,Y,Z) = (0,0,0) is not a valid direction
• This actuator changes the orientation of the object and will conflict with Drot motion unless it is
placed BEFORE the Drot motion actuator (the order of actuator is important). - This actuator doesn't
change the location and speed. It is compatible with gravity.
• All parameters are accessible through Python.
Force Field
Log Message:
BGE patch: new force field constraint actuator
A new type of constraint actuator is available: Force field.
It provides a very similar service to the Fh material feature
but with some specificities:
- It is defined at the object level: each object can have
different settings and you don't need to use material.
- It can be applied in all 6 directions and not just -Z .
- It can be enabled/disabled easily (it's an actuator) .
- You can have multiple force fields active at the same time
on the same object in different direction (think of a
space ship in a tunnel with a repulsive force field
on each wall) .
- You can have a different damping for the rotation.
Besides that it provides the same dynamic behavior and the
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Reference
Constraint Actuator
parameters are self explanatory.
It works by adapting the linear and angular velocity: the
dynamic is independent of the mass. It is compatible with
all other motion actuators.
Note: linear and anysotropic friction is not yet implemented,
the only friction will come from the object damping parameters.
Support for friction will be added in a future revision.
Constraint Actuator Python Functions
returns
Function
Explanation
integer
getDamp
getDamp() Returns the damping parameter.
3-tuple
getDirection
getDirection() Returns the reference direction of the orientation constraint as a
3-tuple.
float
getDistance
getDistance() Returns the distance parameter
integer
getLimit
getLimit() Returns the type of constraint.
float
getMax
getMax() Returns the upper value of the interval to which the value is clipped.
float
getMin
getMin() Returns the lower value of the interval to which the value is clipped.
integer
getOption
getOption() Returns the option parameter.
string
getProperty
getProperty() Returns the property parameter.
float
getRayLength
getRayLength() Returns the length of the ray
integer
getRotDamp
getRotDamp() Returns the damping time for application of the constraint.
integer
getTime
getTime() Returns the time parameter.
setDamp
setDamp(duration) - duration: integer Sets the time constant of the orientation and
distance constraint. If the duration is negative, it is set to 0.
setDirection
setDirection(vector) - vector: 3-tuple Sets the reference direction in world
coordinate for the orientation constraint.
setDistance
setDistance(distance) - distance: float Sets the target distance in distance
constraint
setLimit
setLimit(type) - type: integer 1 : LocX 2 : LocY 3 : LocZ 7 : Distance along +X
axis 8 : Distance along +Y axis 9 : Distance along +Z axis 10 : Distance along -X
axis 1 1 : Distance along -Y axis 12 : Distance along -Z axis 13 : Align X axis 14 :
Align Y axis 15 : Align Z axis Sets the type of constraint.
setMax
setMax(upper_bound) - upper_bcmnd: float Sets the upper value of the interval to
which the value is clipped.
setMin
setMin(lower_bound) - lower_bcmnd: float Sets the lower value of the interval to
which the value is clipped.
setOption
setOption(option) - option: integer Sets several options of the distance constraint.
Binary combination of the following values: 64 : Activate alignment to surface
128 : Detect material rather than property 256 : No deactivation if ray does not hit
target 512 : Activate distance control
setProperty
setProperty(property) - property: string Sets the name of the property or material
for the ray detection of the distance constraint. If empty, the ray will detect any
colliding object.
setRayLength
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Ipo Actuator
Ipo Actuator
setRayLength(length) - length: float Sets the maximum ray length of the distance
constraint
setRotDamp
setRotDamp(duration) - duration: integer Sets the time constant of the orientation
constraint. If the duration is negative, it is set to 0.
setTime
setTime(duration) - duration: integer Sets the activation time of the actuator. The
actuator disables itself after this many frame. If set to or negative, the actuator is
not limited in time.
©
X j ipo
: | act4
Q
Flaw
Force
| Add |
Sta1
►
End (
Child
FrameProp:
□
The Ipo Actuator can play the Ipo-curves for the object that owns the Actuator. If the object has a child with
an Ipo (in a parenting chain) and you activate "Child" in the Actuator, the Ipo for the child is also played.
The animation is played from "Sta:" to "End:" (in frames). If you enter a valid Property name in the
"FrameProp:" field this Property will be updated with the current frame number of the Ipo played. Be carefull
with the float Property type, this can hold non whole numbers, which should check with the
"IntervaF'-Propery Sensor.
The Ipo in the game engine will be played with the speed indicated as "FPS:" (frames per second) in the
Display Buttons F12 in the "Formaf'-panel.
The "Force" Button will convert the "Loc" Ipo curves into forces for dynamic objects. When pressed, the "L"
Button appears which cares for applying the forces locally to the objects coordinate system. This can be used
for a nice jumping action or similar.
The Add button, mutually exclusive with Force button. When selected, it activates the Add mode that consists
in adding the Ipo curve to the current object situation in world coordinates, or parent coordinates if the object
has a parent.
Scale Ipo curves are multiplied instead of added to the object current scale. If the local flag is selected, the Ipo
curve is added (multiplied) in the object's local coordinates.
Delta Ipo curves are handled identically to normal Ipo curve and there is no need to work with Delta Ipo
curves provided that you make sure that the Ipo curve starts from origin. Origin means location for Location
Ipo curve, rotation for Rotation Ipo curve and scale 1 for Scale Ipo curve.
"Current object situation" means the object's location, rotation and scale at the start of the Ipo curve. For Loop
Stop and Loop End Ipo actuators, this means at the start of each loop. This initial state is used as a base during
the execution of the Ipo Curve but when the Ipo curve is restarted (later or immediately in case of Loop
mode), the object current situation at that time is used as the new base.
For reference, here is the exact operation of the Add mode for each type of Ipo curve (oLoc, oRot, oScale,
oMat: object's loc/rot/scale and orientation matrix at the start of the curve; iLoc, iRot, iScale, iMat: Ipo curve
loc/rot/scale and orientation matrix resulting from the rotation).
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Reference
Ipo Actuator
Local
Operation
Location
false
newLoc = oLoc+iLoc
true
newLoc = oLoc+oScale*(oMat*iLoc)
Rotation
false
newMat = iMat*oMat
true
newMat = oMat*iMat
Scale
false
newScale = oScale*iScale
true
newScale = oScale*iScale
Add+Local mode is very useful to have dynamic
location/orientation. Of course, dynamics should
object executing complex movement relative to their current
be disabled during the execution of the curve.
Ipo play modes
Play Plays the Ipo from "Sta" to "End" at every positive pulse the Actuator gets. Other pulses received while
playing are discarded.
Ping Pong Plays the Ipo from "Sta" to "End" on the first positive pulse, then backwards from "End" to "Sta"
when the second positive pulse is received.
Flipper Plays the Ipo for as long as the pulse is positive. When the pulse changes to negative the Ipo is played
from the current frame to "Sta".
Loop Stop Plays the Ipo in a loop for as long as the pulse is positive. It stops at the current position when the
pulse turns negative.
Loop End This plays the Ipo repeatedly for as long as there is a positive pulse. When the pulse stops it
continues to play the Ipo to the end and then stops.
Property Plays the Ipo for exactly the frame indicated by the property named in the field "Prop:".
Ipo Actuator Python Functions
returns
Function
Explanation
integer
getEnd()
Returns the frame at which the ipo stops playing.
bool
getForceIpoActsLocal()
Return whether to apply the force in the object's local coordinates
rather than the world global coordinates.
bool
getIpoAsAdd()
Returns whether to interpret the ipo as additive rather than
absolute.
bool
getIpoAsForce()
Returns whether to interpret the ipo as a force rather than a
displacement.
integer
getStart()
Returns the frame from which the ipo starts playing.
integer
getType()
Returns the operation mode of the actuator.
set(type, startframe, endframe,
mode?)
type: Play, PingPong, Flipper, LoopStop, LoopEnd or FromProp
(string) startframe: first frame to use (int) endframe : last frame to
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Reference
Camera Actuator
use (int) mode? : special mode (0=normal, l=interpret location as
force, 2=additive) Set the properties of the actuator.
setEnd(frame)
frame: last frame to use (int) Set the frame at which the ipo stops
playing.
setForcelpoActsLocal (local)
local : Apply the ipo-as-force in the object's local coordinates?
(KX_TRUE, KX_FALSE) Set whether to apply the force in the
object's local coordinates rather than the world global
coordinates.
setlpoAdd(add)
flag (KXJTRUE, KX_FALSE), set whether to interpret the ipo as
additive rather than absolute.
setlpoAsForce(force)
interpret this ipo as a force (KX_TRUE, KX_FALSE) Set
whether to interpret the ipo as a force rather than a displacement.
setProperty(propname)
propname: name of the property (string) Set the property to be
used in FromProp mode.
setStart(frame)
frame: first frame to use (int) Set the frame from which the ipo
starts playing.
setType(mode)
mode: Play, PingPong, Flipper, LoopStop, LoopEnd or FromProp
(string) Set the operation mode of the actuator.
Examples:
• Addlpo. blend
• Jump. blend
IpoFrameProperty .blend
Camera Actuator
Mill: 0.00
" ac!5
3
Height O.OO
1 v h Mast O.oo
□
The Camera Actuator tries to mimic a real cameraman. It keeps the actor in the field of view and tries to stay
at a certain distance from the object. The motion is soft and there is some delay in the reaction on the motion
of the object.
Enter the name of the object that should be followed by the camera (you can also use the Camera Actuator for
non-camera objects) into the "OB:" field. The field "Height:" determines the height above the object the
camera stays at. "Min:" and "Max:" are the bounds of distance from the object to which the camera is allowed
to move. The "X" and "Y" buttons specify which axis of the object the camera tries to stay behind.
Camera Actuator Python Functions
returns
Function
Explanation
float
getHeight
Returns the height value set in the height: field.
float
getMax
Returns the maximum value set in the Max: field.
float
getMin
Returns the minimum value set in the Min: field.
object or
getObject
getObject(name_only =1) name_only - optional arg, when true will return the
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Reference
string
Sound Actuator
KX_GameObject rather then its name Returns the object this sensor reacts to.
bool
getXY
Gets the axis the camera tries to get behind. True = X, False = Y
setHeight
Sets the height value.
setMax
Sets the maximum value.
setMin
Sets the minimum value.
setObject
setObject(object) - object: KX_GameObject, string or None Sets the object this
sensor reacts to.
setXY
Sets axis the camera tries to get behind. l=x, 0=y
Sound Actuator
The Sound Actuator plays a Sound Object loaded using the Sound Buttons (see Section Sound Buttons ). Use
the Menu Button to browse and choose between the Sound Objects in the scene.
X Sound
act6
□
I SO:bird_flap.wav
Play Stop
Volume: 1.000
Pitch: 0.00
*
□
Sound play modes (MenuBut)
Play Stop Plays the sound for as long as there is a positive event from the controller
Play End Plays the sound to the end, when a positive event is send from the controller
Loop Stop Plays and repeats the sound, as long as the controller sends a positive event
Loop End Plays the sound repeatedly, as long as the controller sends a positive event. When the events stops
the sound is played to its end.
Sound Actuator Python Functions
returns
Function
Explanation
string
getFilename()
Gets the name of the sound block we play
float
getGain()
Gets the gain (volume) of the sound
integer
getLooping()
Returns the current loop mode of the actuator
float
getPitch()
Returns the pitch of the sound
float
getRollOffFactorO
Returns the roll off factor (scale for distance) for the sound
integer
getType()
Returns the operation mode of the actuator
pauseSoundQ
Pause the sound
setFilename(string)
Set the name of the sound block
setGain()
Sets the gain (volume) of the sound
setLoopingO
Sets the loop mode of the actuator
setPitchQ
Sets the pitch of the sound
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Reference
Property Actuator
setRollOffFactorO
Sets the roll off factor for the sounds
setType()
Sets the operation mode of the actuator
startSound()
(re)starts the sound
stopSoundQ
stops the sound
Property Actuator
The Property Actuator is meant to assign values to properties or even calculate with properties. See the
Chapter about #Reference .
With the mode-menu you can switch between the three modes of this Actuator.
□
Assign Assigns a value or Expression (given in the "Value" field) to a Property. For example with an
Expression like "Proppy +1" the "Assign" works like an "Add". To assign strings you need to add quotes to
the string ("...").
Add Adds the value or result of an expression to a property. To subtract simply give a negative number in the
"Value:" field.
Property
act7
in
Cop;/
Prop: Proppy
OBrCube
| Prop: Count
□
Copy This copies a Property named "Count" from the Object "Cube" into the Property "Proppy" on the actual
object. This is an easy and safe way to pass information between objects. You cannot pass information
between scenes with this Actuator!
This Actuator provides Python functions to get and set the values and Property-names. However, from Python
it is much easier to access Properties directly.
Property Actuator Python Functions
returns
Function
Explanation
string
getProperty
getProperty(name) Return the property on which the actuator operates.
depends
getValue
getValue() Returns the value with which the actuator operates.
setProperty
setProperty(name) - name: string Set the property on which to operate. If there is no
property of this name, the call is ignored.
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Reference
Edit Object Actuator
setValue
setValue(value) - value: string Set the value with which the actuator operates. If the
value is not compatible with the type of the property, the subsequent action is
ignored.
Edit Object Actuator
©
i«i
X Edit Object acE
■ 1
1 -
& ::>:.;
foB: Add Objecl
m Eni Ofcjsct
Replace Me«n
L
L
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Edit Object
Loe 00 1 0.00
coo
□
This actuator performs actions on Objects itself, like adding new objects, deleting objects, etc. By default the
type of this Actuator is set to "Add Object". With the type-menu you can switch between following types:
Add Object
With this Actuator type you can add new objects to the scene. This can be new enemies, bullets, particles
(numerous small objects, not Blender Particles) etc.
Edit Object acts
Add Object
0. 00
0.00
Tim e:
0,00
□
The Add Object actuator adds an object to the scene. The new object is oriented along the X-axis of the
creating object.
Keep the object you'd like to add on a separate and hidden layer. You will see an error message on the console
or debug output when not following this rule and no object will appear.
Enter the name of the Object to add in the "OB:" field if the entered Object does not exist in the scene Blender
will blank the input field. The "Time:" field determines how long (in frames) the object should exist. The
value "0" denotes it will exist forever. Be careful not to slow down the game engine by generating too many
objects! If the time an object should exist is not predictable, you can also use other events (collisions,
properties, etc.) to trigger an "End Object" for the added object using Logic Bricks.
With the "linV" buttons it is possible to assign an initial velocity to the added object. This velocity is given in
X, Y and Z components. The "L" button stands for local. When it is pressed the velocity is interpreted as local
to the axis of the added object.
Edit Object Actuator Python Functions
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Reference
Edit Object Actuator
returns
Function
Explanation
list [vx,vy,vz]
GetAngularVelocityO
Returns the angular velocity that will be assigned to
the created object.
getLastCreatedObject()
get the object handle to the last created object. This
way you can manipulate dynamically added objects.
list [vx,vy,vz]
getLinearVelocity()
Returns the linear velocity that will be assigned to the
created object.
depends
getObject(name_only =1)
Returns the name of the object that will be added.
name_only - optional arg, when true will return the
KX_GameObject rather then its name
getTime()
Returns the lifetime of the object that will be added.
instant AddObj ect()
immediately add object without delay
setAngularVelocity(vx, vy, vz)
vx: float - vy: float - vz: float - Assign this angular
velocity to the created object.
setLinearVelocity(vx, vy, vz)
vx: float - vy: float - vz: float Assign this velocity to
the created object.
setObject(object)
object: KX_GameObject, string or None Sets the
object that will be added. There has to be an object of
this name. If not, this function does nothing.
setTime(duration)
duration: integer Sets the lifetime of the object that
will be added, in frames. If the duration is negative, it
is set to 0. Zero means unlimited lifetime
Examples: - AddObject.blend
End
□
This type of the Edit Object Actuator simply ends or kills the current Object. This is very useful for ending a
bullet's life after a collision or something similar.
Replace Mesh
X Edft Object ! aciZ
Q
Replace Mesh
ME:
□
This type of the Edit Object Actuator replaces the mesh of the object by another mesh with the given name in
the "ME:" field.. The other mesh must be existent in the scene of course. Use a "Fake User" to ensure that you
can't loose the mesh when working with Logic Bricks.
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Reference
Edit Object Actuator
Motion Actuator Python Functions
returns
Function
Explanation
string
getMeshO
Returns the name of the mesh to be substituted.
instantReplaceMesh()
Immediately replace mesh without delay
setMesh(name)
String or None Set the mesh that will be substituted for the current one.
Track To
Edit Object
@
□
Track to
flt l lMMMMMt l lMMMM I HtMMMM I IIt l t lllH
ad2
j«2
iOB:
Time:
The "Track to" type, rotates the object in such a way that the Y-axis points to the target specified in the "OB:"
field. Normally this happens only in the X/Y plane of the object (indicated by the "3D" button not being
pressed). With "3D" pressed the tracking is done in 3D. The "Time:" parameter sets how fast the tracking is
done. Zero means immediately, values above zero produce a delay (are slower) in tracking.
Track To Actuator Python Functions
returns
Function
Explanation
KX_GameObject or
string
getObject
getObject(name_only =1) name_only - optional arg, when true will
return the KX_GameObject rather then its name Returns the object to
track with the parent of this actuator
integer
getTime
getTime() - time: integer Return the time in frames with which the
tracking motion is delayed.
bool
getUse3D
getUse3D() Returns 1 if the motion is allowed to extend in the
z-direction.
setObject
setObject(object) - object: KX_GameObject, string or None Set the object
to track with the parent of this actuator.
setTime
setTime(time) - time: integer Set the time in frames with which to delay
the tracking motion.
setUse3D
setUse3D(value) - value: or 1 Set to 1 to allow the tracking motion to
extend in the z-direction, set to to lock the tracking motion to the x-y
plane.
Dynamics
I Edit Object
Dynamics
ac!2
-
Restore Dynamics
□
Using this type of the EditObject Actuator you can switch on and off the physical evaluation of the object
carrying the Actuator. This can become handy to speed up things, e.g. disable dynamics for inactive enemies
for example.
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Reference
Scene Actuator
□
Enable/Disable Dynamics switch on/off the whole physical behavior of the object.
Enable/Disable Rigid Body switch on/off the rolling or tumbling physics for the object.
Dynamics Edit Object Actuator Python Functions
returns
Function
Explanation
integer
getOperation
getOperation() -> integer Returns the operation type of this
actuator.
setOperation
setOperation(operation?) - operation? : type of dynamic operation
= restore dynamics 1 = disable dynamics 2 = enable rigid body
3 = disable rigid body Change the dynamic status of the parent
object.
Scene Actuator
Set Scare
Set Camera
Add QverlayScens
Add BackgiauncfScene
Remove Scene
Suspend Scene
Resume Scene
m iiiiiiiiiiiiiiiiiBBa
□
The Scene Actuator is meant for switching Scenes and Cameras in the game engine or adding overlay or
background scenes.
Choose the desired action with the Menu Button and enter an existing camera or scene name into the text
field. If the name does not exist, the button will be blanked!
Reset Simply restarts and resets the scene. It has the same effect as stopping the game with ESC and restarting
with PKEY .
Set Scene Switch to the scene indicated into the text field. Switching will reset the actual scene!
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Reference
Set Camera Switch to the Camera indicated in the "OB:" text field.
Random Actuator
Add OverlayScene Adds the overlay scene indicated in the text field "SCE:", which is rendered on top of all
other (existing) scenes.
Add BackgroundScene Adds a background scene which will be rendered behind all other scenes.
Added Scenes with own lights will add to the light of the base scenes as well. If this is not wanted, remove the
lights from the added scenes or use layered lighting.
Remove Scene Removes a scene.
Suspend Scene Suspends named ("SCE:") scene until "Resume Scene" is called. Be careful not to suspend the
actual scene if there is no other scene to resume!
Resume Scene Resumes a suspended Scene.
Scene Actuator Python Functions
returns
Function
Explanation
string
getCamera()
Return the name of the camera to switch to.
string
getSceneQ
Return the name of the scene the actuator wants to switch to.
bool
getUseRestart()
Return whether the scene will be restarted.
setCamera(camera) -
camera: string Set the camera to switch to.
setExecutePriorityO
None
setScene(scene)
scene: string Set the name of scene the actuator will switch to.
setUseRestart(flag)
flag: or 1. Set flag to 1 to restart the scene.
Random Actuator
An often-needed function for games is a random value to get more variation in movements or enemy
behavior.
actio
< Seed: 1 » | Bool Constant
: Property
Always Irue
J
□
The "Seed"-parameter is the value fed into the random generator as a start value for the random number
generation. Because computer generated random numbers are only "pseudo" random (they will repeat after a
(long) while) you can get the same random numbers again if you choose the same Seed.
A seed of zero means no random at all!
Enter the name of the property you want to be filled with the random number into the "Property:" field.
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Reference
Random Actuators types
Random Actuator
Boolean Constant This is not a random function at all, use this type to test your game logic with a TRUE or
FALSE value.
Boolean Uniform This is the classic random 50-50 pick. It results in TRUE or FALSE with an equal chance.
This is like an (ideal) flip of a coin.
Boolean Bernoulli This random function results in a boolean value of TRUE or FALSE, but instead of
having the same chance for both values you can control the chance of having a TRUE pick with the "Chance"
parameter. A chance of 0.5 will be the same as "Bool Uniform". A chance of 0.1 will result in 1 out of 10
cases in a TRUE (on average).
Integer Constant For testing your logic with a value given in the "Value:" field
Integer Uniform This random type randomly produces an integer value between (and including) "Min:" and
"Max:". The classical use for it is to simulate a dice pick with "Min: 1" and "Max: 6".
Integer Poisson The random numbers are distributed in such a way that an average of "Mean:" is reached
with an infinite number of picks.
Float Constant For debugging your game logic with a given value.
Float Uniform This returns a random floating point value between "Min:" and "Max:".
Float Normal Returns a weighted random number around "Mean:" and with a standard deviation of "SD:".
Float Negative Exponential Returns a random number which is well suited to describe natural processes like
radioactive decay or lifetimes of bacteria. The "Half-life time:" sets the average value of this distribution.
XXX Actuator Python Functions
returns
Function
Explanation
integer
getDistribution()
Returns the type of the active distribution.
depends
getParal()
Returns the first parameter of the active distribution.
Refer to the documentation of the generator types for
the meaning of this value.
depends
getPara2()
Returns the first parameter of the active distribution.
Refer to the documentation of the generator types for
the meaning of this value.
string
getProperty(name)
Return the property to which the random value is
assigned. If the generator and property types do not
match, the assignment is ignored.
integer
getSeed()
Returns the initial seed of the generator. Equal seeds
produce equal series.
setBoolBernouilli(value)
value: a float between and 1 Return false value *
100%% of the time.
setBoolConst(value)
value: or 1 Set this generator to produce a constant
boolean value.
setBooiUniformQ
Set this generator to produce true and false, each with
50%% chance of occuring
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Reference
Message Actuator
setFloatConst(value)
value: float Always return value
setFloatNegativeExponential(half_life)
half_life: float Return negative-exponentially
distributed numbers. The half-life 'time' is characterized
by half_life.
setFloatNormal(mean,
standard_deviation)
mean: float - standard_deviation: float Return
normal-distributed numbers. The average is mean, and
the deviation from the mean is characterized by
standard_deviation.
setFloatUniform(lower_bound,
upper_bound)
lower_bound: float - upper_bound: float Return a
random integer between lower_bound and
upper_bound.
setlntConst(value)
value: integer Always return value
setlntPoisson(value)
value: float Return a Poisson-distributed number. This
performs a series of Bernouilli tests with parameter
value. It returns the number of tries needed to achieve
success.
setIntUniform(lower_bound,
upper_bound)
lower_bound: integer - upper_bound: integer Return a
random integer between lower_bound and
upper_bound. The boundaries are included.
setProperty(name)
name: string Set the property to which the random
value is assigned. If the generator and property types do
not match, the assignment is ignored.
setSeed(seed)
seed: integer Set the initial seed of the generator. Equal
seeds produce equal series. If the seed is 0, the
generator will produce the same value on every call.
Examples: - RandomActuator.blend
Message Actuator
X 1 Message y MessageSender
— gHanH
O
I To:
| Subject: Display
Iff jBody: -Hello Worldr
□
This LogicBrick sends a message out, which can be received and processed by the Message Sensor.
The "To:" field indicates that the message should only be sent to objects with the given name.
The subject of the message is indicated in the "Subject:" field. With these two possibilities you can control the
messaging very effectively.
The body (content) of the message can either be a text ("Body:") string or the content of a Property when
"T/P" is activated ("Propname:"). See Section [#MessageBody] on how to read the body of a message with a
simple Python, script.
Message Actuator Python Functions
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Reference
Game Actuator
returns
Function
Explanation
setBody
Sets the body of the message.
setBodyType
Sets whether the body should be text or a Property name.
setSubject
Sets the subject of the message.
setToPropName
Sets the property name the message should be send to
Game Actuator
With the Game Actuator you can load new levels from disk, quit or restart a game.
□
Start: Blender, the Blenderplayer or a Blender executable will load the named file from disk and start it. To
pass information between the actual and loaded level see #GameLogic.globalDict .
Restart: Restarts the current scene. All information is reset!
Quit: Quits a game. Inside Blender you will be back in the editing of the scene, in Blenderplayer or in
executables you will return to operating system level. The quit function es especially important if you
redefined the ESC key !
Load/Save GameLogic.globalDict: Loads/Saves the global directory to save game states. See
#GameLogic , globalDict .
XXX Actuator Python Functions
returns
Function
Explanation
string
getFile
getFile() get the name of the file to start.
setFile
setFile(name) set the name of the file to start.
Visibility Actuator
VI*
t'isitjility
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aci14
□
This actuator allows you to make an object visible or invisible. Visible/invisible Recursive will make all child
objects visible/invisible.
To change visibility from a Python script use the function setVisibilityO from the game object
(controller.getOwner().setVisible(visible,recursive)).
2D Filter Actuator
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Reference
2D Filter Actuator
□
The 2D Filter Actuator is somehow special, because it works on the whole game. You can add it to any object
and the whole image (real time) -rendered will be affected.
Currently there are some simple 2d filters and the possibility to add your own shader scripts.
Built-in Filters: Motion Blur, Blur, Sharpen, Dilation, Erosion, Laplacian, Sobel, Prewitt, Gray Scale, Sepia
and Invert.
Custom Filters
Custom filters give you the ability to define your own 2d filter using GLSL. Its usage is the same as built-in
filters, but you must select "Custom Filter" in 2D Filter actuator, then write a shader program into the Blender
Text Editor and enter the shader script name.
For more information on the OpenGL Shading Language (GLSL) see GLSL specification on opengl.org.
You can also use these uniform variables in your shader program:
Variable
Usage
bgl_RenderedTexture
uniform sampler2D bgl_RenderedTexture;
bgl_TextureCoordinateOffset
uniform vec2 bgl_TextureCoordinateOffset[9];
bgl_Texture Width
uniform float bgl_Texture Width;
bgl_TextureHeight
uniform float bgl_TextureHeight;
Example Shader Program: Blue Sepia
uniform sampler2D bgl_RenderedTexture;
void main (void)
{
vec4 texcolor = texture2D (bgl_RenderedTexture, gl_TexCoord [ ] . st ) ;
float gray = dot (texcolor . rgb, vec3 (0 . 299, 0.587, 0.114));
gl_FragColor = vec4 (gray * vec3(0.8, 1.0, 1 . 2 ), texcolor . a) ;
Parent Actuator
□
The Parent Actuator sets or removes a parent relationship between two objects. The logic must be in the child
object.
Set Parent: Sets a parent relationship between the object carrying the Actuator and the object named in the
"OB: "-field which is then the parent (controlling object)..
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Remove Parent Removes the parent relation
Parent Actuator
XXX Actuator Python Functions
returns
Function
Explanation
KX_GameObject or string
getObject
getObject(name_only =1) name_only - optional arg, when
true will return the KX_GameObject rather then its name
Returns the object that is set to.
setObject
setObject(object) - object: KX_GameObject, string or
None, sets the object to set as parent.
Examples: - ParentActuator. blend
State Actuator
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□
The State Actuator allows to set states (see [[#State Actuator])
Cpy Copies the selected states from the Actuator to the general state. This will overwrite all states with the
ones set in the Actuator.
Add Add the selected states to the general state
Sub Subtract the selected states from the general state
Inv Inverting the selected states bitwise. See Examples
XXX Actuator Python Functions
returns
Function
Explanation
setMask(mask)
mask : bits that will be modified Set the value that defines the bits that will be
modified by the operation. The bits that are 1 in the value will be updated in the
object state, the bits that are are will be left unmodified expect for the Copy
operation which copies the value to the object state.
setOperation(op)
op : bit operation (0=Copy, l=Set, 2=Clear, 3=Negate) Set the type of bit
operation to be applied on object state mask. Use setMask() to specify the bits
that will be modified.
Examples:
• InvStateActuator.blend
• StateDebug.blend
Game engine Python
Python is an interpreted, interactive, object-oriented programming language.
Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high
level dynamic data types, and dynamic typing. Python is also usable as an extension language for applications
that need a programmable interface.
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Beside this use as an extension language, the Python implementation is portable to (at least) all platforms that
Blender runs on.
Python is copyrighted but freely usable and distributable, even for commercial use.
In Blender there are two incarnations of the Python integration: Blender Python meant for extending Blender
and its modeling and animation tools and the BGE Python meant to be used with real time content.
Text Window
The Text Window is a simple but useful text editor, fully integrated into Blender. It's main purpose of it is to
write Python scripts, but it is also very useful for writing comments in the Blendfile or to explain the purpose
of the scene to other users.
The Text Window can be displayed with SHIFT-F1 1 or by adjusting the WindowType menu in the
WindowHeader.
iport SaineLogici
3
4 cent = SameLogic-getCurrentEontrol lerO
6 me = coiH-getttunerO
8 ■ ■ ' . d i f me
10 sensor = cont.getSensejr("sensor")
11 actuator = cent- get Actuator 1 ! "act" '
o
i
[I.!! »| •* Filt Edit Formal p]i|-j*B|ft| j^TXiGelCccs \x | | Screen IS | Tab 4 | Text Internal
□
In the Text Window Header there is the file menu for opening, saving and executing Python scripts. In the
Edit menu you can find the common functions to copy&paste, search&replace etc. The Format menu will
assist you in formating the code which is especially important because Python uses the indentation to mark
code blocks.
The first Icon in the Text Window Header will make the Text Window fullscreen, this can also be done with
the keyboard CTRL-UP and CTRL-DOWN.
The next icon switches on the line numbers, which is very helpful for programming and debugging.
The icon right to the line number icon will enable a word wrap, good for typing longer texts in the Text
Window.
The "AB" buttons enables syntax highlighting for python keywords.
The icon with the (Python-) snake on it enables the use of Python text plug ins.
The next buttons can be used to browse between text files, open new ones or add new text buffers. The
"X"-shaped Button deletes a text buffer.
With the Button (labeled "Screen 15" in the figure above) on the right side you can change the font used to
display the text.
You can scroll the text using the scrollbar on the left, using SHIFT-MMB and mouse movements or using the
mouse wheel.
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Reference Text Window
By holding LMB and then dragging the mouse you can mark ranges of text for the usual cut, copy & paste
functions. The key commands are:
ALT-C Copies the marked text into a buffer
ALT-X Cuts out the marked text into a buffer
ALT-V Pastes the text from buffer to the cursor in the Text Window
ALT-O Loads a text, a FileWindow appears
CTRL-R Reloads the current text, very useful for editing with an external editor
SHIFT-ALT-F Pops up the Filemenu for the Text Window
ALT-F Find function
ALT -J Pops up a Number Button where you can specify a line number that the cursor will jump to
ALT-U Unlimited Undo for the Text Window
ALT-R Redo function, recovers the last Undo
ALT -A Marks the whole text
BGE Python
With Python integrated into the game engine you can influence Logic Bricks, change their parameters and
react to events triggered by the Logic Bricks.
Besides that you can influence the GameObject that carries the Python Controller directly. This means moving
it, applying forces or getting information from this object.
In addition to the Python in the game engine, Blender includes Python for modeling and animation tasks,
which is not covered here.
Basic Blender Game Engine Python
The first step for using Blender game engine (BGE) Python is to add at least a Sensor and a Python Controller
to an object. Then add a new text file in the Text Window. Fill in the name of that text file into the "Script:"
field of the Python Controller. You should now have a game logic setup like in this Figure.
□
Logic Bricks for a first game Python script
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Reference BGE Python
Now enter the following script into the Text Window (you don't need to type the lines starting with "#", these
are comments).
# first BGE Python script
# gets the position of the object
# and prints it to the console
import GameLogic
cont = GameLogic . getCurrentController ( )
me = cont . getOwner ( )
print me . getPosition ( )
Listing [!xxx]. First Simple Script
The result of the "print" command and errors from the Python interpreter will appear on the console from
which you started Blender from, or in the DOS window, when running Blender from Windows. So it is
helpful to size the Blender window in such a way that you can see the console window while programming
Python.
This basic script only prints the position of the object that owns the Python Controller. Move your object and
then restart the game engine with the PKEY to see the results changing, or attach a Motion Actuator to the
object to move it..
Now for an explanation of the script line by line. Line five is an important line. We import the "GameLogic"
module which is the basis for all game Python in Blender.
In fact every script executed from the game engine will import this script without the need of this line.
However it is good style to import it, so one can immediately see that this is a BGE Python. Also using
"import GameLogic as GL" and writing "GL.xxx" later is a nice time saver.
In line seven we ask with "getCurrentControllerO" for a pointer to the Controller which executes the script
and do assign it to the variable "cont". You can see "getCurrentControllerO" is a function provided by the
module "GameLogic".
In line eight we use the controller we got in line seven to get the owner, meaning the GameObject carrying the
LogicBrick. You can see we use the method "getOwner()" provided by the controller to get the owner of our
controller.
We now have a pointer to the owner of the Controller and we can use its methods to do things with it. Here in
line 10 we use the "getPosition()" method to print the position of the GameObject as a matrix of the X, Y and
Z values.
You may now wonder what other methods the PythonObjects have. Of course this is part of this
documentation, but Python is "self" documenting, so we have other ways to get that information.
Add the following line to the end of the script from Figure 28-3:
print dir (owner)
Start the game engine again, stop it and look at the console window. You will see the following output:
[0.0, 0.0, 0.0]
[ ' alignAxisToVect ' , ' applylmpulse ' , ' disableRigidBody ' , ' enableRigidBody ' , 'endObject',
' getAngularVelocity ' , ' getAxisVect ' , ' getChildren ' , ' getChildrenRecursive ' , ' getDistanceTo ' ,
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Reference
BGE Python
' getLinearVelocity ' , 'getMass', 'getMesh', ' getName ' , ' getOrientation ' , 'getParent', ' getPhys
' getPosition ' , ' getPropertyNames ' , ' getReactionForce ' , 'getState', 'getVectTo', ' getVelocity '
' getVisible ' , 'isA', ' rayCast ' , 'rayCastTo', ' removeParent ' , ' restoreDynamics ' ,
' setAngularVelocity ' , ' setCollisionMargin ' , ' setLinearVelocity ' , ' setOrientation ' , ' setParent
' setPosition ' , 'setState', ' setvisible ' , ' suspendDynamics ' ]
The first line shows the position of the object, the next lines show the methods, that the "owner" provides. For
example you see a 'getMass' method, which will return the mass of a dynamic object. With the knowledge of
the "dir()" function you can ask Python objects for information, without consulting external documentation.
Examples:
• FirstBGEPython.blend
• FirstBGEPythonl. blend
Actuator Access
The next step for our quick introduction to BGE Python is the access for Actuators. Generally it is possible to
change values in the Actuators and to activate or deactivate the Actuator from within Python.
□
Build a logic as shown in the figure above. Make sure that you enter a value for "Rot", or nothing will move
in our example. Then change the python script or enter a new one as shown in the listing below.
It is a good style to name the Logic Bricks to make the logic clear and to avoid errors in scripts
# BGE Python script
#
# Access to the Actuator
import GameLogic
cont = GameLogic . getCurrentController ( )
me = cont . getOwner ( )
moveit = cont . getActuator ( "Moveit " )
GameLogic . addActiveActuator (moveit, 1 )
Listing [!xxx]. Actuator Access
In line 10 you can see how an Actuator is accessed. The Controller variable "cont" provides a "getActuator()"
function. We pass it the name of the Actuator as string. It it possible to have numerous Actuators connected to
a Controller, so a good talking name will help here to avoid confusion. The next line now uses a function from
the GameLogic module "addActiveActuator()" to enable the Actuator. The parameters are first the variable
holding the Actuator and a "1" to enable the Actuator. In the rare case where you need to stop an Actuator you
would pass a "0".
When everything is entered correctly and the Logic Bricks are connected the right way (and named according
to the script), you can press PKEY to start the game engine. The cube should now rotate. Of course this is
much easier with a simple AND-Controller, but in the next step we will do something which is not possible
with only Logic Bricks.
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Reference BGE Python
Properties and Actuators
Imagine you want to speed up an object slowly. With Logic Bricks there is no simple way to achieve this, but
with some Python it is easy to do.
E
Add Property
Dei Fioaa - Nameupeea
i inn
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□
First we add a Property (see #Properties ) by clicking on the "Add Property" button left of the Logic Bricks of
our small testscene. Leave the type to "Float" and name the property "speed", this Property will hold the
current speed (I will use rotation speed) of our object. You should also activate the "D" button, this will show
the property in the 3DView while the game is running. This is usually only done when the 3DView is not in
textured mode, so check that you are in wireframe or solid mode. If you want to see the Debug output also in
textured mode use the Game-menu to activate "Show Debug Properties".
Now change the existing script:
# BGE Python script
#
# Access to the Actuator
import GameLogic
cont = GameLogic . getCurrentController ( )
me = cont . getOwner ( )
moveit = cont . getActuator ( "Moveit " )
me . speed = me. speed + 0.0005
moveit .setDRot (0, 0, me. speed, 1)
GameLogic . addActiveActuator (moveit, 1 )
Listing: Properties and changing Actuators
You may have wondered what line 8 was used for in the previous script, it was just left in for convenience,
but now we use the variable "me" which is holding a pointer to our object to access the Property we created in
the Logic Buttons. In line 12 we add "0.0005" every time the script is called to the property "speed". This will
make "speed" count up in very small steps, however, since the script gets called every l/60th of a second it
will count up quite fast.
In line 14 we now set the Rot value for the Z-axis with the "speed" value. The first three argument values to
"setDRot()" are the rotation around X, Y and Z. The fourth argument denotes if the rotation should be around
the local axis ("1") or global axis ("0"). This is the Python counterpart to the "L" button in the Motion
Actuator.
Sensor Access
For completeness I will now demonstrate how to access a sensor from Pyton.
# BGE Python script
#
# Access to the Actuator
import GameLogic
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Reference
cont = GameLogic . getCurrentController ( )
me = cont . getOwner ( )
moveit = cont . getActuator ( "Moveit " )
always = cont . getSensor ( "Always" )
if always . isPositive ( ) :
me. speed = me . speed + 0.0005
moveit. setDRot (0, 0, me . speed, 1)
GameLogic . addActiveActuator (moveit , 1 )
GameLogic Module
Listing [!xxx]. Sensor Access
This looks very similar like the Actuator Access. In line 1 1 we get a pointer to the Sensor named "Always"
into a variable and can now use its functions. Here we just use "isPositive()" which will only return "true" if
the Sensor fires a positive event. In this case it is again just for demonstrating and will not provide extra
functionality. But in the case of other sensor types or the case that there are more sensors connected to the
Python-Controller this function will help us very much.
See the file "FirstBGEPython6.blend" for an example with two KeyboardSensors controlling the rotational
speed of the object.
GameLogic Module
The GameLogic module is the base of all game logic by Python.
GameLogicModule
returns
Function
Explanation
addActiveActuator
addActiveActuator(actuator,bool)
string
expandPath(path)
Converts a blender internal path into a proper file system path, path -
the string path to convert. Use / as directory separator in path You can
use '//' at the start of the string to define a relative path; Blender
replaces that string by the directory of the startup .blend or runtime
file to make a full path name (doesn't change during the game, even if
you load other .blend). The function also converts the directory
separator to the local file system format.
int
getAverageFrameRate()
Gets the estimated average frame rate
list
getBlendFileList(path)
Gets a list of blend files in the same directory as the current blend file
or the list from "path"
controller
getCurrentControllerO
gets the current controller (the one "owning" the script)
scene
getCurrentScene()
getCurrentScene() Gets a reference to the current scene.
integer
getLogicTicRate()
Gets the logic tic rate
integer
getPhysicsTicRate()
Gets the physics tic rate
float
getRandoniFloatO
returns a random floating point value in the range [0..1)
diet
globalDict()
dict() -> new empty dictionary, dict(mapping) -> new dictionary
initialized from a mapping object's (key, value) pairs, dict(seq) -> new
dictionary initialized as if via: d = { } for k, v in seq: d[k] = v
dict(**kwargs) -> new dictionary initialized with the name=value
pairs in the keyword argument list. For example: dict(one=l, two=2)
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Reference
Rasterizer Module
setGravity(x,y,z)
set Gravitation
setLogicTicRate()
Sets the logic tic rate
setPhy sic sTicRate( )
Sets the physics tic rate
Rasterizer Module
Module
returns
Function
Explanation
disableMotionBlur()
disable motion blur
enableMotionBlur()
enable motion blur
enableVisibility()
enable visibility
float
getEyeSeparation()
get the eye separation for stereo mode
float
getFocalLength()
get the focal length for stereo mode
string
getGLSLMaterialSetting(string)
get the state of a GLSL material setting
getMaterialMode()
get the material mode being used for OpenGL rendering
integer
getWindowHeight()
get window height (see Trackball.blend)
integer
getWindowWidth()
get window width
makeScreenshot(path)
make screenshot, saved in format as denoted in the Display
Buttons
set AmbientColor( " [r ,g ,b , a] " )
set Ambient Color
setBackgroundColor("[r,g,b,a]")
set Background Color
setEyeSeparation(float)
set the eye separation for stereo mode
setFocalLength(float)
set the focal length for stereo mode
setGLSLMaterialSetting()
set the state of a GLSL material setting
setMaterialMode()
set the material mode to use for OpenGL rendering
setMistColor()
set Mist Color (rgb)
setMistEnd()
set Mist End(rgb)
setMistStart()
set Mist Start(rgb)
setMousePosition(x,y)
set mouse position
showMouse(bool)
show mouse in game engine mode
GameLogic.globalDict
This is a place where data can be stored even when new blend files are loaded. This was developed for
Apricot, so Frankie can go into levels in new blendfiles keeping his inventory.
The GameLogic.globalDict is a Python directory, dictionaries are sometimes found in other languages as
"associative memories or "associative arrays. Unlike sequences, which are indexed by a range of numbers,
dictionaries are indexed by keys, which can be any immutable type
Here is a small example using a dictionary (from the official Python documentation at [3D :
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Reference
>>> tel = {'jack': 4098, ' sape ' : 4139}
>>> tel [ 'guido' ] = 4127
>>> tel
{'sape': 4139, 'guido': 4127, 'jack': 4098}
>>> tel [ ' jack' ]
4098
>>> del tel [ ' sape' ]
>>> tel [ 'irv' ] = 4127
>>> tel
{'guido': 4127, 'irv': 4127, 'jack': 4098}
>>> tel. keys ()
['guido', 'irv', 'jack']
>>> tel . has_key (' guido ' )
True
>>> 'guido' in tel
True
GameLogic.globalDict
Loading and saving the GameLogic.globalDict can be done with the Game Actuator. You can access the
global data with Python like this:
# Save data before changing levels
# gets data from a Property to globalDict
GameLogic . globalDict [ ' SavedScore ' ] = me . actualscore
Don't forget a "Save GameLogic.globalDict" with the Game Actuator before changing levels. In the new level
we now have to do "Load GameLogic.globalDict" with the Game Actuator an can then access the saved data:
# load data after loading a level
# gets data from globalDict to a Property
me . actualscore = GameLogic . globalDict [' SavedScore ' ]
Examples:
• GlobalDict_Ll. blend (press A to "score", loads the next level at score=5 and the score is keept in
Level 2)
• GlobalDict_L2.blend (Level 2)
GameKeys Module
This module holds key constants for the Keyboard Sensor.
PhysicsConstraints Module
This python module, PhysicsConstraints, gives access to internal physics settings that influence quality of the
rigid body dynamics
createConstraint (Edge Constraint)
createConstraint( objl_PhysicsID, obj2_PhysicsID, constraintType, edgePos_x, edgePos_y,
edgePos_z, edgeAngle_x, edgeAngle_y, edgeAngle_z ) objl_PhysicsID: integer (The physics ID of
object 1) obj2_PhysicsID: integer (The physics ID of object 2) constraintType: integer = No
constraint. 1 = Point constraint. 2 = Edge constraint. 11 = Vehicle constraint edgePos_x: float
(Blender unit) edgePos_y: float (Blender unit) edgePos_z: float (Blender unit) edgeAngle_x: float
(Range: -1.0 to 1.0) edgeAngle_y: float (Range: -1.0 to 1.0) edgeAngle_z: float (Range: -1.0 to 1.0)
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Reference PhysicsConstraints Module
Position (edgePos_x, edgePos_y, edgePos_z) Where do you want the center of the edge to be located?
(Distance from objl's object center)
Angle (edgeAngle_x, edgeAngle_y, edgeAngle_z) In what direction do you want the edge to point? (Uses
obj 1 's axis)
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene ( ) . getOb jectList ( )
# get object named Obj_l
objl = objList ["OBObj_l"]
# get object named 0bj_2
obj2 = objList ["0B0bj_2"]
# want to use Edge constraint type
constraintType = 2
# get Obj_l physics ID
objl_ID = ob jl . getPhysicsId ( )
# get 0bj_2 physics ID
obj2_ID = obj2 . getPhysicsId ( )
# Use bottom right edge of Obj_l for hinge position
edgePos_x = 1.0
edgePos_y = 0.0
edgePos_z = -1.0
# use Obj_l y axis for angle to point hinge
edgeAngle_x = 0.0
edgeAngle_y = 1.0
edgeAngle_z = 0.0
# create an edge constraint
PhysicsConstraint s . createConstraint ( objl_ID, obj2_ID,
constraintType,
edgePos_x, edgePos_y, edgePos_z,
edgeAngle_x, edgeAngle_y, edgeAngle_z )
Example:
• EdgeConstraint.blend
createConstraint (Point Constraint)
createConstraint( objl_PhysicsID, obj2_PhysicsID, constraintType, pointPos_x, pointPos_y,
pointPos_z) objl_PhysicsID: integer (The physics ID of object 1) obj2_PhysicsID: integer (The
physics ID of object 2) constraintType: integer = No constraint. 1 = Point constraint. 2 = Edge
constraint. 11 = Vehicle constraint pointPos_x: float (Blender unit) pointPos_y: float (Blender unit)
pointPos_z: float (Blender unit)
Poin t Position (pointPos_x, pointPos_y, pointPos_z)
nn
Where do you want the pivot point to be located? (Distance from obj 1 's object center)
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Reference PhysicsConstraints Module
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene ( ) . getOb jectList ( )
# get object named Obj_l
objl = objList ["OBObj_l"]
# get object named 0bj_2
obj2 = objList ["0B0bj_2"]
# want to use point constraint type
constraintType = 1
# get Obj_l physics ID
objl_ID = ob jl . getPhysicsId ( )
# get 0bj_2 physics ID
obj2_ID = obj2 . getPhysicsId ( )
# Use bottom right front corner of objl for point position
pointPos_x = 1.0
pointPos_y = -1.0
pointPos_z = -1.0
# create a point constraint
PhysicsConstraint s . createConstraint ( objl_ID, obj2_ID,
constraintType,
pointPos_x, pointPos_y, pointPos_z)
Example blend: PointConstraint.blend
createConstraint (Vehicle Constraint)
createConstraint(objl_PhysicsID, obj2_PhysicsID, constraintType ) objl_PhysicsID: integer (The
physics ID of the vehicle) obj2_PhysicsID: integer (Set this to zero) constraintType: integer = No
constraint. 1 = Point constraint. 2 = Edge constraint. 11 = Vehicle constraint.
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene (). getOb jectList ( )
# get object named Car
objCar = objList [ "OBCar" ]
# want to use vehicle constraint type
constraintType = 11
# get car physics ID
carlD = objCar . getPhysicsId ( )
# create a vehicle constraint
PhysicsConstraint s . createConstraint ( carlD, 0, constraintType)
Example blend: VehicleConstraint.blend
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Reference PhysicsConstraints Module
getAppliedlmpulse
getAppliedlmpulse(constraintld) Returns the applied impulse. Return type: float constraintld: integer
Save the constraintID when the constraint is created.
Sample Code:
1st script
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene ( ) . getOb jectList ( )
# get object named Car
objCar = ob jList [ "OBCar" ]
# want to use vehicle constraint type
constraintType = 11
# get car physics ID
car_ID = ob jCar . getPhysicsId ( )
# create a vehicle constraint
carConst = PhysicsConstraints . createConstraint ( car_ID, 0, constraintType)
# get the constraint ID
carConst_ID = carConst . getConstraintld ( )
# save the constraint ID as a objCar variable
ob jCar . constraint_ID = carConst_ID
#### rest of script
2nd script
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene (). getOb jectList ( )
# get object named Car
objCar = objList [ "OBCar" ]
# get car constraint ID that was saved
carConst_ID = objCar . constraint_ID
# get the applied impulse
appliedlmpulse = PhysicsConstraints . getAppliedlmpulse (carConst_ID)
getVehicleConstraint
getVehicleConstraint(constraint_ID) Returns the vehicle constraint ID. constraint_ID: integer
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
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Reference PhysicsConstraints Module
objList = GameLogic . getCurrentScene ( ) . getOb jectList ( )
# get object named Car
objCar = ob jList [ "OBCar" ]
# want to use vehicle constraint type
constraintType = 11
# get car physics ID
car_ID = ob jCar . getPhysicsId ( )
# create a vehicle constraint
carConst = PhysicsConstraints . createConstraint ( car_ID, 0, constraintType)
# get the constraint ID
carConst_ID = carConst . getConstraintld ( )
# get vehicle constraint
car = PhysicsConstraint s . getVehicleConstraint (carConst_ID)
removeConstraint
removeConstraint(constraint_ID) Removes the constraint. constraint_ID: integer
Save the constraintID when the constraint is created.
This removes the constraint between 2 game objects (point and edge constraints). It does not remove vehicle
constraints.
Sample Code:
Part 1 : Create a Point Constraint
######### PointConstraint.py
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene (). getOb jectList ( )
# get object named Obj_l
objl = objList ["OBObj_l"]
# get object named Obj_2
obj2 = objList ["OBObj_2"]
# want to use point constraint type
constraintType = 1
# get Obj_l physics ID
objl_ID = objl . getPhysicsId ( )
# get Obj_2 physics ID
obj2_ID = obj2 . getPhysicsId ( )
# Use bottom right front corner of objl for point position
pointPos_x = 1.0
pointPos_y =-1.0
pointPos_z = -1.0
# create a point constraint
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Reference PhysicsConstraints Module
constraint = PhysicsConstraints . createConstraint ( objl_ID, obj2_ID,
constraint Type,
pointPos_x, pointPos_y, pointPos_z)
# get the constraint ID
constraint_ID = constraint . getConstraintld ( )
# save the constraint ID as an Obj_l variable
ob j 1 . constraint_ID = constraint_ID
Part 2: Remove constraint script
########### RemoveConstraint . py
# import PhysicConstraint s Module
import PhysicsConstraints
# get object list
objList = GameLogic . getCurrentScene ( ) . getOb jectList ( )
# get object 1
objl = objList ["OBObj_l"]
# get constraint ID that was saved as an Obj_l variable
# when the constraint was created
constraint_ID = ob j 1 . constraint_ID
# remove constraint
PhysicsConstraints . removeConstraint (constraint_ID)
Example blend: RemoveConstraint.blend
setDeactivationTime
setDeactivationTime(time) Time (in seconds) after objects with velocity less then thresholds (see
below) are deactivated time: float
This affects every object in the scene, except for game objects that have 'No sleeping' turned on.
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# set the deactivation time
PhysicsConstraints . setDeactivationTime (1.0)
setDeactivationLinearTreshold
setDeactivationLinearTreshold(linearTreshold) Sets the linear velocity that an object must be below
before the deactivation timer can start. linearTreshold: float
This affects every object in the scene, except for game objects that have 'No sleeping' turned on.
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# set the deactivation linear velocity threshold
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Reference PhysicsConstraints Module
PhysicsConstraint s .setDeactivationLinearTreshold(l.O)
setDeactivationAngularTreshold
setDeactivationAngularTreshold(angularTreshold) Sets the angular velocity that an object must be
below before the deactivation timer can start. angularTreshold: float
This affects every object in the scene, except for game objects that have 'No sleeping' turned on.
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# set the deactivation angular velocity threshold
PhysicsConstraints . setDeactivationAngularTreshold (1.0)
setGravity
setGravity(gx, gy, gz) Sets the gravity for the scene, gx: float (force of gravity on world x axis) gy:
float (force of gravity on world y axis) gz: float (force of gravity on world z axis)
This affects every object in the scene that has physics enabled.
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# Beam me up ! !
# set gravity to a +10.0 on z axis
PhysicsConstraints. setGravity ( 0.0, 0.0, 10.0)
Example blend: SetGravity .blend
setLinearAirDamping
setLinearAirDamping(damping) Sets the linear air resistance for all objects in the scene, damping:
float Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# set linear air resistance to 30.0
PhysicsConstraints . setLinearAirDamping (30.0)
setNumlterations
setNumlterations(numlter) Sets the number of times an iterative constraint solver is repeated.
Increasing the number of iterations improves the constraint solver. It will descrease performance,
numlter: integer Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# repeat iterative solvers 10 times
PhysicsConstraints . setNumlterations (10)
setNumTimeSubSteps
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Reference Message Body
setNumTimeSubSteps(numSubStep) Increasing the number of time substeps improves the quality of
the entire physics simulation, including collision detection and constraint solver. It will decrease
performance. Set the number of timesubsteps to to suspend simulation numSubStep: integer
Sample Code:
# import PhysicConstraint s Module
import PhysicsConstraints
# set time sub steps to 2
PhysicsConstraints . setNumTimeSubSteps (2 )
Message Body
One of the most asked things with the messaging system in Blender is how to get the message body. In the
Message Actuator we can send a text or the content of a Property but there is no function to retrieve this with
Logic Bricks.
So here we need a small script.
# The message sensor has to be named "message"
# body will go in existing Property "mbody"
# The message body will be converted to the type of the Property
# Only the last (if there are more than one messages send)
# body will be stored!
from types import *
cont = GameLogic . getCurrentController ( )
mess = cont . getSensor ( "message" )
me = cont . getOwner ( )
if mess . isPositive ( ) :
bodies = mess. getBodies()
if bodies ! =None :
for body in bodies:
if type (me .mbody ) is StringType:
mbody = body me .
else :
mbody = float <
Simple script to get the message body
This needs to be connected to a Message Sensor called "message". Fill in the Subject field as needed.
However, this simple script will not work properly if more than one message arrives in one frame. All but the
last message will be discarded. See the score counting mechanism in the pinball tutorial files how to avoid
this.
Example:
• MessageBody.blend
• See also in the Pinball Tutorial files
About blend files in this book
You can get the .blend files this book refers to downloading this ZIP file (286. 3M)
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Appendix
Getting Blender
The central place to get Blender is at http://www.blender.org/download/get-blender/ . For this book it is
recommended to use Blender 2.48a for which the book was written. Future Blender versions may contain
enhancements or changes which can be confusing for beginners.
Installation of Blender
To install Blender, download the appropriate package for your platform to your computer. The Windows
version comes with an optional self-extracting installer, for other operating systems you can unpack the
compressed file to the location of your choice.
Provided the Blender binary is in the original extracted directory, Blender will run straight out of the box. No
system libraries or system preferences are altered.
If you are unsure which version to choose use the 32-bit Installer for Windows or use the Blender packet
provided by your Linux distribution.
Getting Support
The download packages containing a blender.html file with installation instructions and a quick survival guide
for new users.
All support links are collected at http://www.blender.org/education-help/
The support is done mostly on user forums and ire chat, so don't hesitate to ask there! Links to the major sites
are in the link section.
Of course there is a huge list of Blender books and tutorial DVDs which can be bought in the Blender e-shop
or at your local book store.
Blender Foundation and Institute
Goals
The Blender Foundation is an independent organisation (a Dutch "stichting"), acting as a non-profit public
benefit corporation, with the following goals:
• To establish services for active users and developers of Blender
• To maintain and improve the current Blender product via a public accessible source code system
under the GNU GPL license
• To establish funding or revenue mechanisms that serve the foundation's goals and cover the
foundation's expenses
• To give the worldwide Internet community access to 3D technology in general, with Blender as a core
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Appendix Organization
Organization
The Blender Foundation has offices in the Amsterdam Blender Institute. Revenues from e-shop and
publishing enable Ton Roosendaal and a small staff to work full-time on Blender, organize activities like for
Siggraph or the Blender Conference, support development/documention projects, and pay for bookkeeping
and administration expenses. The main activities for Blender are organized in boards and projects.
Links to the Blender Community, Books and Websites
• blender.org
• Blender Multiplayer Game and Tutorial http://www.wsag.ch.vu/
• Download some example files for soft bodies
http://bulletphvsics.com/ftp/pub/test/index.php ?dir=blender/&file=blender-2.48-gamesoftbodv-preview9-samp
• Blender Artists Forum http://blenderartists.org/forum/
• Bullet Physics Library http://bulletphvsics.com
• CGTextures http://cgtextures.com/
• Blender Nation http://www.blendernation.com/
• Blender Artists http://blenderartists.org/
• Blendpolis, big german community http://blendpolis.de/f/blender.php
• German Blender book "Das Blender-Buch", 3rd Edition, http://blenderbuch.de/
• Game Engine Python http://www.tutorialsforblender3d.com/index.html
• Lots of stuff, Books, Training DVDs, Goodies: Blender e-shop http://www.blender3d.org/e-shop/
• Artist Christopher Plush http://theboomshelter.com/
Glossary
Active
Blender makes a distinction between selected and active. Only one Object or item can be active at any
given time, for example to allow visualization of data in buttons. See Also: Selected.
Actuator
A LogicBrick that acts like a muscle of a lifeform. It can move the object, or also make a sound. See
Section 27.3. See Also: LogicBrick, Sensor, Controller.
Alpha
The alpha value in an image denotes opacity, used for blending and antialiasing.
Anti-aliasing
An algorithm designed to reduce the stair-stepping artifacts that result from drawing graphic
primitives on a raster grid.
Back-buffer
Blender uses two buffers in which it draws the interface. This double-buffering system allows one
buffer to be displayed, while drawing occurs on the back-buffer. For some applications in Blender the
back-buffer is used to store color-coded selection information.
Bevel
Beveling removes sharp edges from an extruded object by adding additional material around the
surrounding faces. Bevels are particularly useful for flying logos, and animation in general, since they
reflect additional light from the corners of an object as well as from the front and sides.
Bounding box
A six-sided box drawn on the screen that represents the maximum extent of an object.
Channel
Some DataBlocks can be linked to a series of other DataBlocks. For example, a Material has eight
channels to link Textures to. Each IpoBlock has a fixed number of available channels. These have a
name (LocX, SizeZ, enz.) which indicates how they can be applied. When you add an IpoCurve to a
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Appendix Glossary
channel, animation starts up immediately.
Child
Objects can be linked to each other in hierarchical groups. The Parent Object in such groups passes its
transformations through to the Child Objects.
Clipping
The removal, before drawing occurs, of vertices and faces which are outside the field of view.
Controller
A LogicBrick that acts like the brain of a lifeform. It makes decisions to activate muscles (Actuators),
either using simple logic or complex Python scripts. See Section 27.2. See Also: LogicBrick, Sensor,
Python, Actuator.
DataBlock (or "block")
The general name for an element in Blender's Object Oriented System.
Doppler effect
The Doppler effect is the change in pitch that occurs when a sound has a velocity relative to the
listener. When a sound moves towards the listener the pitch will rise, when going away from the
listener the pitch will drop. A well known example is the sound of an ambulance passing by.
Double-buffer
Blender uses two buffers (images) to draw the interface in. The content of one buffer is displayed,
while drawing occurs on the other buffer. When drawing is complete, the buffers are switched.
Edit Mode
Mode to select and transform vertices of an object. This way you change the shape of the object itself.
Hotkey: TAB. See Also: Vertex (pi. vertices).
Extend select
Adds new selected items to the current selection (SHIFT-RMB)
Extrusion
The creation of a three-dimensional object by pushing out a two-dimensional outline and giving it
height, like a cookie-cutter. It is often used to create 3-D text.
Face
The triangle and square polygons that form the basis for Meshes or for rendering.
FaceSelectMode
Mode to select faces on an object. Most important for texturing objects. Hotkey: FKEY
Flag
A programming term for a variable that indicates a certain status.
Flat shading
A fast rendering algorithm that simply gives each facet of an object a single color. It yields a solid
representation of objects without taking a long time to render. Pressing ZKEY switches to flat shading
in Blender.
FPS
Frames per second. All animations, video, and movies are played at a certain rate. Above ca. 15fps the
human eye cannot see the single frames and is tricked into seeing a fluid motion. In games this is used
as an indicator of how fast a game runs.
Frame
A single picture taken from an animation or video.
Gouraud shading
A rendering algorithm that provides more detail. It averages color information from adjacent faces to
create colors. It is more realistic than flat shading, but less realistic than Phong shading or ray-tracing.
The hotkey in Blender is CTRL-Z.
Graphical User Interface (GUI)
The whole part of an interactive application which requests input from the user (keyboard, mouse
etc.) and displays this information to the user. Blenders GUI is designed for a efficient modeling
process in an animation company where time equals money. Blenders whole GUI is done in OpenGL.
See Also: OpenGL.
Hierarchy
Objects can be linked to each other in hierarchical groups. The Parent Object in such groups passes its
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transformations through to the Child Objects.
Ipo
The main animation curve system. Ipo blocks can be used by Objects for movement, and also by
Materials for animated colors.
Ipo Curve
The Ipo animation curve.
Item
The general name for a selectable element, e.g. Objects, vertices or curves.
Keyframe
A frame in a sequence that specifies all of the attributes of an object. The object can then be changed
in any way and a second keyframe defined. Blender automatically creates a series of transition frames
between the two keyframes, a process called "tweening."
Layer
A visibility flag for Objects, Scenes and 3DWindows. This is a very efficient method for testing
Object visibility.
Link
The reference from one DataBlock to another. It is a "pointer" in programming terminology.
Local
Each Object in Blender defines a local 3D space, bound by its location, rotation and size. Objects
themselves reside in the global 3-D space. A DataBlock is local, when it is read from the current
Blender file. Non-local blocks (library blocks) are linked parts from other Blender files.
Logic Brick
A graphical representation of a functional unit in Blender's game logic. LogicBricks can be Sensors,
Controllers or Actuators. See Also: Sensor, Controller, Actuator.
Mapping
The relationship between a Material and a Texture is called the 'mapping'. This relationship is
two-sided. First, the information that is passed on to the Texture must be specified. Then the effect of
the Texture on the Material is specified.
Mipmap
Process to filter and speed up the display of textures.
ObData block
The first and most important DataBlock linked by an Object. This block defines the Object type, e.g.
Mesh or Curve or Lamp.
Object
The basic 3-D information block. It contains a position, rotation, size and transformation matrices. It
can be linked to other Objects for hierarchies or deformation. Objects can be "empty" (just an axis) or
have a link to ObData, the actual 3-D information: Mesh, Curve, Lattice, Lamp, etc.
OpenGL (OGL)
OpenGL is a programming interface mainly for 3D applications. It renders 3-D objects to the screen,
providing the same set of instructions on different computers and graphics adapters. Blenders whole
interface and 3-D output in the real-time and interactive 3-D graphic is done by OpenGL.
Parent
An object that is linked to another object, the parent is linked to a child in a parent-child relationship.
A parent object's coordinates become the center of the world for any of its child objects.
Perspective view
In a perspective view, the further an object is from the viewer, the smaller it appears. See orthographic
view.
Pivot
Pixel
A point that normally lies at an object's geometric center. An object's position and rotation are
calculated in relation to its pivot-point. However, an object can be moved off its center point,
allowing it to rotate around a point that lies outside the object.
A single dot of light on the computer screen; the smallest unit of a computer graphic. Short for
"picture element. "
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Appendix Glossary
Plug-In
A piece of (C-)code loadable during runtime. This way it is possible to extend the functionality of
Blender without a need for recompiling. The Blender plugin for showing 3D content in other
applications is such a piece of code.
Python
The scripting language integrated into Blender. Python is an interpreted, interactive, object-oriented
programming language.
Render
To create a two-dimensional representation of an object based on its shape and surface properties (i.e.
a picture for print or to display on the monitor).
Rigid Body
Option for dynamic objects in Blender which causes the game engine to take the shape of the body
into account. This can be used to create rolling spheres for example.
Selected
Blender makes a distinction between selected and active objects. Any number of objects can be
selected at once. Almost all key commands have an effect on selected objects. Selecting is done with
the right mouse button. See Also: Active, Selected, Extend select.
Sensor
A LogicBrick that acts like a sense of a lifeform. It reacts to touch, vision, collision etc. See Section
27.1. See Also: LogicBrick, Controller, Actuator.
Single User
DataBlocks with only one user.
Smoothing
A rendering procedure that performs vertex-normal interpolation across a face before lighting
calculations begin. The individual facets are then no longer visible.
Transform
Change a location, rotation, or size. Usually applied to Objects or vertices.
Transparency
A surface property that determines how much light passes through an object without being altered.
See Also: Alpha.
User
When one DataBlock references another DataBlock, it has a user.
Vertex (pi. vertices)
The general name for a 3-D or 2-D point. Besides an X,Y,Z coordinate, a vertex can have color, a
normal vector and a selection flag. Also used as controlling points or handles on curves.
Wireframe
A representation of a three-dimensional object that only shows the lines of its contours, hence the
name "wireframe."
X, Y, Z axes
The three axes of the world's three-dimensional coordinate system. In the FrontView, the X axis is an
imaginary horizontal line running from left to right; the Z axis is a vertical line; and Y axis is a line
that comes out of the screen toward you. In general, any movement parallel to one of these axes is
said to be movement along that axis.
X, Y, and Z coordinates
The X coordinate of an object is measured by drawing a line that is perpendicular to the X axis,
through its centerpoint. The distance from where that line intersects the X axis to the zero point of the
X axis is the object's X coordinate. The Y and Z coordinates are measured in a similar manner.
Z-buffer
For a Z-buffer image, each pixel is associated with a Z-value, derived from the distance in 'eye space'
from the Camera. Before each pixel of a polygon is drawn, the existing Z-buffer value is compared to
the Z-value of the polygon at that point. It is a common and fast visible-surface algorithm.
15/02/2011 12:39:15 238
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